Tactics training helps a lot. I like echess[1], it has a good selection of tactical puzzles. Try to solve one a day and you should see significant improvement in your game within a month.
For a game against an advanced player you must master the openings which can be hard (I always make mistakes in the opening stages).
For a game against an advanced player you must master the openings which can be hard (I always make mistakes in the opening stages).
[1]http://en.lichess.org/training/17424