sam i have told you wat to do many times.

1. Develop your pieces
2. Castle
3. Play people around your rating or slightly better
4. Play me more :P

In as many words, I have two recommendations:

1. Play people who are better than you.  Not hopelessly better, unless you're looking for some coaching, but significantly better.  The reward is greater: the rating system will reward you fairly if you win against someone of any level - more points if they're rated higher than you, and fewer if they're rated lower.  But the added bonus is that playing higher-rated people will challenge you to become better yourself.  Apart from (and even probably including) dedicating yourself to a bit of studying, that's the surest way.

2. This goes for everyone who wants to become more serious about their game.  Get more serious.  Take more time per move.  Think more deeply about every turn you take.  Your latent strengths will come to the surface, and you will start to realize your latent potential.

You can study endgames or tactics too if you want, but don't underestimate the effect that these two points above will have on your long-term growth as a player.