Winning a pawn, trading material and winning the endgame is probably the most common way of winning...so you're not doing anything wrong there. I would suggest studying tactics mostly, but also learning the middlegame plans for the openings that you play. What should you do when theory ends? Play on the kingside/queenside? Pawn attack vs Piece Play? Which squares do your pieces belong on and what weaknesses should you be attacking?
All of these questions and more can be answered by studying the plans behind the openings you play.
So here's the deal:
I'm a begginer (~1200) and by now I've corrected most of the normal flaws newbies have. I almost never blunder, I antecipate my opponents next moves so when I lose (and I lose quite a bit) its normally because I missed a tactic or because my endgame strenght is quite low.
I hear a lot of people saying that begginers shouldn't worry about learning openings but the truth its the part of chess I enjoy the most, so I've looked into them quite a bit.
As a result, I normally get an advantage in this part of the game, even against opponents rated quite higher than me (1500)
By advantage I mean I normally get a few of these:
The problem is that once I reach the middle game I feel a little bit lost and I don't know what I should do. I respond to threats but I fail to create my own. My plan consists normally of trading off pieces and grabbing a pawn or two so that I reach a winning end game, and I've won many games this way, even agaist players rated 200 \ 300 points higher than me (live chess normally).
However, I feel that this "batte plan" fails me often, so I'd like some suggestions
Anybody?