[TimM]

A lot of decent and standard advice so far. I would say that it is important not to let any one area of your game get way ahead or fall way behind the others.

At this point, don't worry about speed chess. As you gain experience at slower games you will be able to play faster naturally.

For openings, study just enough specific variations to stay out of trouble. It won't do much good if you are great in the middlegame and ending but keep falling into opening traps. Try to get an idea of the basic plans the openings you play. To do this, play through a lot of complete annotated master games in these openings. This is important because your opening choice pretty much determines your strategic goals for the rest of the middlegame.

It is also good to spend a little time explore openings you don't play in the same way, just so you get exposed to other plans which don't often come up in your games, and also just to see if you wouldn't like some other openings better.

Your middlegame and endgame will also be helped by studying these complete games.

Solving tactical problems as others mentioned here goes without saying.

Going over your games also helps. When I started playing at a live chess club (funny to call it that, there were no online chess sites in 1983), it was very helpful to go over the games with my opponents. I would also study these games at home, looking for improvements, seeing if I missed wins, or if I allowed my opponents wins that they missed.

If you want, post a game of yours that you thought was interesting. It will give a much better idea of what you need to work on than your own description.