Yeah, that's the way I tend to play a lot too, but it's wrong. There are typical plans associated with every opening, often associated with so called "pawn breaks" and you just have to learn them. Tempo is very important to good players, but the mediocre tend to play a bit timidly because they don't understand positional play and can't always recognize opportunities for advantage. You can get better of course just by playing, but there's also the danger that you just end up perfecting your mistakes. No, the sad truth is that you have to study the game to get better. Luckily there are resources everywhere. I really like the Lessons on chess.com and don't mind paying $100 a year for unlimited access to them, but there are plenty of free resources around as well. Best of luck!
stuck and making stupid mistakes

The first big hurdle is forming good calculation habits. More than defending pieces, it's the ability to punish basic mistakes, and the ability to avoid making those basic mistakes yourself. Specifically it's calculating "forcing moves" which are checks, captures, and threats. So after your opponent moves, you check to see whether you can punish that move by surveying all of your moves that are a check, capture, or threat.
And then any time before you make your move, imagine your candidate move as if it's been made, and check for all of your opponent's checks, captures, and threats to see all the ways they can punish your candidate move. If you still like your move, then you can play it.
This is Dan Heisman's idea, not mine, which he's mentioned in articles and books, but it's so often misquoted and it's referenced so many times that google isn't giving me many good results for "hope chess" so I'm explaining it myself instead of giving you a link. For example many people think "hope chess" is making a threat and hoping your opponent doesn't see it. That's not it. It's making a move without checking for checks, captures, and threats, and then hoping your opponent can't immediately win the game.
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Anyway, on average it probably takes a few years to form good calculation habits, but kids and people who spend multiple hours a day on chess can form them much faster. I like to recommend this book:
https://www.amazon.com/Back-Basics-Tactics-ChessCafe-Chess/dp/1888690348
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The second big hurdle, IMO, is becoming a well rounded player... and this can (in fact should) be worked on simultaneously with trying to form good calculation habits. Well rounded meaning you've studied strategy, endgames, annotated GM games, and openings as well as tactics. So those are the 5 categories.
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As far as this isn't chess as you remember it, I'll give you a bird's eye view of what chess is when masters are playing. It goes something like this:
1) First players increase the mobility of pieces (bringing them off the back rank, typically where they influence the center)
2) Players open lines with pawn breaks. This is a chess term essentially meaning pawns are exchanged, which clears files, diagonals, and ranks (collectively called lines). With open lines your mobile pieces can infiltrate.
3) Players infiltrate or otherwise bring their pieces into contact with the opponent's weaknesses. There are two main types of weaknesses: pawns that can't be defended by a friendly pawn and the king. Both are slow moving which makes them typical weaknesses.
4) The last phase, those weak pawns fall so a player wins material, or the weak king falls and is checkmated. If you've won material you can typically force a pawn to queen in the endgame and after that checkmate isn't far off.
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The common thread throughout is piece activity. At first piece activity means simple mobility, and notice this goes to the heart of chess itself. A queen is worth more than a rook because it's more mobile. In later phases "piece activity" means being in contact with vulnerable targets. When you read a strategy book it's mostly concerned with identifying weaknesses, and then typical maneuvers and plans to increase your piece activity and pressure those weaknesses.
Having said that, at a beginner level, chess is more about the basics... was my opponent's last move a mistake? Is my candidate move a mistake? That will take up most of the bandwidth of your conscious thought in the beginning.
Hope that answers your question.

Ok my last post was pretty long. If you just want to have more of a clue and beat your friends then here's a cliff note's version of basic chess strategy. Choose an area (kingside, center, or queenside) and attack there. Choose an area where you have more advanced pawns than your opponent, or more active pieces than your opponent... preferably both.
In the diagram below the pawns are telling white to attack on the kingside and telling black to attack on the queenside. Sometimes this advice is given as "attack in the direction your pawns point."
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After you decide, play a pawn break.
In the diagram below, white's pawn breaks are f4 and b4. Black's are f5 and b5.
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And remember, pawn breaks favor the side who is better developed or the side who has more active pieces in that area.
In the position below, either pawn break f3 or f4 is winning for white. It may seem counterintuitive because black seems to be attacking on the knigside, but pawn breaks favor the side which is better developed, or the side with more mobile pieces in that area.
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And that's typically how attacking in the correct area when you have an advantage goes... in other words winning tactics will more or less appear from nothing. Suddenly the opponent will have no moves to save himself.
So after being “forced” to watch the queens gambit by my girlfriend, it’s given me the urge to take up the game again. I played quite regularly all the way through school and I was pretty decent but that was over 20 years ago so you can imagine my strength now. I’ve played a few games online now and the problem I seem to run into is that we will both play the openings,defend all our pieces and then it’s just a waiting game where more often than not I’ll make a stupid mistake due to time pressure and lose the game. Is this the essence of the game? Is there a strategy to stop this happening? Like I said I’ve been absent for so long but I don’t remember it being like this...
Any comments/advise is greatly appreciated.
Best
Liam.