I wouldn't totatally abandon blitz. It doesn't "hurt' your chess game. When you get better you could warm up by playing a few bullet games, not really caring about making the best move but just making moves trying not to lose anything in the opening and trying to avoid getting mated. Don't do that yet! That probably won't have much benefit to you as your low blitz rating shows that you lack an adequete chess knowledge for bullet to be benficial. I would say warming up to a few 3 minutes wouldn't hurt, then a couple 5 minutes, then 10 minutes, and 30 if you want. I personally think 30 minute games are boring, but apparently that is where real chess is played. Eventually I will try and work on my slow game ;)
I do have a good correspondance rating though... so idk...
Anyway, back to what I was saying. The downfall with blitz is when you play nothing but blitz you start to develop bad habits, like making unnessisary pawn or piece moves, or make pointless checks. Part of the strategy of blitz is to make those type of unnessisary moves to get a gain on time. Time is King in blitz, so you sacrifice good moves with bad decisions sometimes just to get a gain on time. Blitz is half about making a good move, and half about getting a gain on time. A good blitz player, knows how to manage his time well by constantly glancing at the clock on his opponents turn to get a gauge for how much of a time advantage or disadvange he or she has. I didn't play much chess when I started playing over the board with long games, so I can't really say I got good just by playing long games, my skills actually improved the most when I played blitz, however, that came over the course of 10 years, and I am still not very good at all considering. So taking that into consideration, just playing blitz, without studying, leaves you at a disadvantage. I recommend playing both blitz and long games, so you get better at both, because I think when you stick to doing just long games you tend to become boring, making games last for 2 hours, like someone I know... Nobody likes that, don't be that person that makes chess games take 2 hours over the board!
Also once you get to a certain level in blitz, especially on chess.com, it starts to become less and less about skill and more about speed to an extent, especially if you are playing with premoves. You see I won a lot of games recently and surprising gained 100 rating points just because I started doing premoves. Sure I made bad premoves at times, and other times I made good premoves. However, it's how you handle the bad ones that creates an opportunity for your opponent to get a bit frustrated with how much time you have on your clock and ends up making blunders where you just win anyway :)... So yeah, not a lot of real chess happening especially when premoves come into play sometimes in blitz, but it's fun once you get the hang of it :D. Blitz is about two things:
1.) Fun
2.) Sharpening your mind
It's a good tool to sharpen your mind, as fluid IQ is only accurately measured in chess with time contraints. If you where to play a slow game, you would be using more of your learned accumulated chess knowledge, rather than raw calculating ability. Unless of course you are one of those people that can think 20 moves in your head, that's another thing entirely... Hats off to people who can look at the board and can picture the pieces moving in their mind 20 moves ahead, that is the skill of the big boys at the long game! That's something to look forward to kid, but now, just focus on tactics tactics tactics, and learn basic end game stuff like what was mentioned. I'd like to recommend a book called "303 tricky chess tactics" by fred wilson and Bruce Albeston. Right now you have to learn tactics, plain and simple. The reason why you are scoring so low on the tactics trainer is because you are not aquainted with very many tactics. After going through that book around 50 times, you'll be able to spot a lot more tactics. That's actually a book I myself am reading right now btw! It will help you to!
Remember the first rule of chess is to develop, never move the same piece twice in the opening unless you are creating some kind of threat, knights before bishops, and notice the structure of your pawns in every game as in the future pawn structure will be something you will need to really focus on. Don't worry too much about pawn structure now, beyond trying to avoid doubled pawns, isolated pawns, hanging pawns, look those up :D. There are good articles here that talk about all of these things but unless you pay chess.com you will not be able to read or view all of them. If you can afford it, and get a paid chess.com membership, I would say it will really help your game if you go through the desktop study plan for beginners, as it shows you the basics and beyond. I went through a good chunk of it and it even helped me. The information there is very good.
I lose a lot as well. I would forget blitz chess and play some correpsondence based chess on here which gives you several days to think about your moves. Chess takes ages to master and the best way to learn from your losses. Best thing to do is learn to spot patterns which lead to mate. There is a good book called "How to Beat your Dad at Chess" by Murray Chandler. It gives 50 mating patterns with commentary and teaches you how to use them. A lot of people, even quite good players can be suckered by them. You just have to spot the opportunities. Bobby Fischer teaches chess is another good book for beginners as is Bruce Pandolfini's Ulitmate guide to chess. If you have a chessboard at home I STRONGLY advise playing through some games. There is a book called Logical Chess: Move by Move by Irving Chernev which has games with each move explained in a simple and entertaining manner. It really give an insight into the power of the pieces even if the games are pretty old now. However I am not about to start playing fancy defences and openings as learner.
I hear what you are saying though. I am always caught out by people rushing their queens out and menacing my developed pieces. It is no fun. Best thing is to play people of similar ability to yourself and that is quite hard online as it is in liffe :(