Endgame knowledge is better to study than Opening Knowledge. Start with King and Pawn Endgames.
Question about end game training

There's an argument that the endgame should be studied FIRST.
Unless there is a direct mating attack, it's hard to make sensible middle-game decisions unless you already know what a winning endgame looks like... and it's hard to make sensible opening decisions unless you already know what a winning middle-game looks like.
Perhaps you should study first the endgame, then the middle-game, and the opening last of all.
Also end game can be taught exactly, middle game is often a quenstion of style and opening is a matter of fashion.
Well, it is highly debatable whether you should start with endgame study. Let's look at it from a practical point of view. At the 800 level there are almost no endgames that you'll play with equal material. Almost every time you do reach an endgame, someone will be multiple pawns if not a piece or more up. Where is the value then in knowing how to win a K+1pawn vs K position?
At your level, I'd start of with tactics, tactics and more tactics. Some general middlegame strategy is not bad either. For the endgame I think it's enough to know how to checkmate with K+R vs K etc. When you start reaching the endgames with similar material, you'll want to learn a bit about king and pawn endgames. How to win and how to draw the king + 1 pawn vs king endgames is important, because then you know whether you can trade down to this kind of endgame. That could be a few hundred points down the road still.

Well, it is highly debatable whether you should start with endgame study. Let's look at it from a practical point of view. At the 800 level there are almost no endgames that you'll play with equal material. Almost every time you do reach an endgame, someone will be multiple pawns if not a piece or more up. Where is the value then in knowing how to win a K+1pawn vs K position?
At your level, I'd start of with tactics, tactics and more tactics. Some general middlegame strategy is not bad either. For the endgame I think it's enough to know how to checkmate with K+R vs K etc. When you start reaching the endgames with similar material, you'll want to learn a bit about king and pawn endgames. How to win and how to draw the king + 1 pawn vs king endgames is important, because then you know whether you can trade down to this kind of endgame. That could be a few hundred points down the road still.
Thanks for the help! Years ago, I got close to 1300 in rating, so I'm not a complete beginner. The gold membership only allows for 25 puzzles a day. Is this a good amount for a hobbyist? I don't have a lot of time, but I was thinking that I'd do 20 min worth of checkmate puzzles each weekday, in the evenings, using a book that has over 5,000 chess puzzles in it (I love these puzzles so much!), and I'd play a few games on the weekend.
Do whatever you feel is fun, cause only that way you can keep it up. Doing 10 mins of tactics every other day can already be a great way to improve.

My dad taught me how to play chess when I was 8 years old. On my 2nd day he taught me how to win with king and rook vs a lone king and also how to win with king and queen vs a lone king. That was basic and very easy--so you should at least learn that.
But other than that you should learn not to blunder in the opening or middle game.
I'm not sure that I believe the old saying that you should study endgames first. But it's undoubtedly true that the if you don't know how to win--or defend--basic endgames, you're throwing a lot of points and half-points away for nothing. And since calculation is a vital chess skill, the end game is an excellent place to start learning to calculate deeply

Knowing how to play basic, and then not-so-basic endgames can make a huge difference in the number of games you win (or the number of draws you salvage).
But even beyond the value within the endgame, understanding endgames can help you figure out how to play middlegames. If you can accurately tell that such-and-such combination allows you trade down to an endgame you can reilably win (or draw if you feel that's the best the position will allow), that can considerably simplify your middlegame decisions.

I have a question. Back when I played regularly, I always thought the end game was the hardest part of chess. It seemed easier to checkmate mid-game than to try and calculate things during the end game.
How do you calculate?
Now that I'm taking up chess as a hobby again, I'm wondering, at what point should I start learning end game stuff?
Start asap, on beginner level endgames.
Start on tactics AND other skills also.
Should I play lots of games and develop the ability to see a certain number of steps ahead before working on end game (which seems to require the ability to see many moves in advance)?
Visualization is another skill (imo)
Or, is opening theory more important?
Another...skill, not more important but not necessarily less either.
Also, I used to love checkmate puzzles (I have a book with 5,000 of them), so I think I'm okay with that part.
Puzzles can help improve multiple skills, depending on the puzzles and your methods.
Edit:
Simply playing lots of games may or may not help.
Your level of competition will determine how much potential there is.

@PerpetuallyPinned: I calculate by visualizing the moves that I can make and I keep track of what my opponent is doing. Okay, I'll try some beginner level end games. I'm good at art, and graphic design, so I think I have an edge with visualization...or maybe not... I might take a glorious beating when I start playing.

@ponz111 and @Laskersnephew and @tlay80: Thanks for the feedback. I think I'll try and do some basic end game training. And a ton of checkmate puzzles too.
In Silman's complete endgame course he recommends for beginners (0-999) to know the following endgames: 1) Q+R vs. K 2) 2 rooks vs. K 3) Q vs. K 4) R vs. K For 1000-1200, one should know: - Q vs B - Q vs N - basic pawn endings = K+P vs K (opposition, rule of the square, how to win or hold a draw, special cases of rook pawns (a+h)) I guess, once you're familiar with those, you're good to go.

In Silman's complete endgame course he recommends for beginners (0-999) to know the following endgames: 1) Q+R vs. K 2) 2 rooks vs. K 3) Q vs. K 4) R vs. K For 1000-1200, one should know: - Q vs B - Q vs N - basic pawn endings = K+P vs K (opposition, rule of the square, how to win or hold a draw, special cases of rook pawns (a+h)) I guess, once you're familiar with those, you're good to go.
Thanks for the info!
A question for anyone; Does chess.com store a list of all my forum posts, so I can find this one again?

I'm not a titled player, but my unprofessional opinion is that you want to balance your study of opening, midgame, and endgame. They just all effect each other. If you know what endgames are winning, losing, or drawing, it can help you decide in the middlegame if you want to accept or decline certain trades or position your pieces a certain way. And while I agree with the advice to not do too deep a dive in opening theory, you need to know some as every game will have an opening and tactics are only possible with well placed pieces.
But the reality is that my endgame knowledge is what I use the least in my games. Even at my level at 1500's as well as in my games vs 1600's, one player will have gained through tactics or a superior position either a large material advantage or a mating net before the game gets to an endgame. I probably only get a somewhat close endgame in maybe 10% of my games. And even though I haven't played a ton of 1700-1800 players, none of my games with them (including the ones i win) do they end in endgames with close material. My suspicion is that they probably don't crack 50% of games with a materially close endgame either. And so i think that reason more than any other is behind the advice for beginners to not put too much focus on endgames. Practice what you might see in a game, and what I have seen in my climb to 1500s are far more games won and lost on tactics and positional principles than endgame knowledge.

I'm not a titled player, but my unprofessional opinion is that you want to balance your study of opening, midgame, and endgame. They just all effect each other. If you know what endgames are winning, losing, or drawing, it can help you decide in the middlegame if you want to accept or decline certain trades or position your pieces a certain way. And while I agree with the advice to not do too deep a dive in opening theory, you need to know some as every game will have an opening and tactics are only possible with well placed pieces.
But the reality is that my endgame knowledge is what I use the least in my games. Even at my level at 1500's as well as in my games vs 1600's, one player will have gained through tactics or a superior position either a large material advantage or a mating net before the game gets to an endgame. I probably only get a somewhat close endgame in maybe 10% of my games. And even though I haven't played a ton of 1700-1800 players, my suspicion is that they probably don't crack 50% of games with a materially close endgame either. And so i think that reason more than any other is behind the advice for beginners to not put too much focus on endgames. Practice what you might see in a game, and what I have seen in my climb to 1500s are far more games won and lost on tactics and positional principles than endgame knowledge.
We're just more consistent 1600s...
I agree with comments on a balanced approach that includes endgame study. Silman's endgame book sets out the material according to rating and recommends mastering the chapters up to your rating and maybe the next one if you're keen. Then put the book away and work on other areas until your overall chess improves. I like his pragmatic approach. If you'd like a structured guide that helps you work on what is most relevant for your level then give it a try. I find Chessable is a good site for learning the basic techniques, they have a number of free courses.

There's plenty of helpful resources relating to endgame here.....as well as all the other facets of the game...
Improving Your Chess - Resources for Beginners and Beyond...
https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond
I have a question. Back when I played regularly, I always thought the end game was the hardest part of chess. It seemed easier to checkmate mid-game than to try and calculate things during the end game.
Now that I'm taking up chess as a hobby again, I'm wondering, at what point should I start learning end game stuff? Should I play lots of games and develop the ability to see a certain number of steps ahead before working on end game (which seems to require the ability to see many moves in advance)? Or, is opening theory more important?
Also, I used to love checkmate puzzles (I have a book with 5,000 of them), so I think I'm okay with that part.