9 days ago I posted this. Dramatically, I gain +236 in 4 rounds and become a master right after falling all the way down to expert. It's quite impressive and I would like to share some experiences, hope this can help you.
1.Do not solve too many easy problems. For instance, you should be more focused on *1900 — *2200 problems if you are a cm and want to become master. I had solved 250 *800 problems before I even realized it (I guess it's because I used to virtual participated a lot but rarely tried to work out problems I didn't solve after vp), and it turns out to be a total waste of time.
2.I find it helpful to make myself solve some problems every day and keep the profile green. Sometimes I do *800 problems to keep this (remember: do not make it a routine!) when I am really busy, such as participating in ICPC and CCPC, but it does make me solve a lot more problems than before, because I am kind of lazy and would not be that eager to solve problems without this motivation.
3.Participate in official rounds as long as you can. The idea is that the more rounds you participate in, the more accurately the rating reflects your true cp skill. So when next time you are making excuses like "I am afraid of losing my rating/I don't feel myself today...", maybe you should give it a second thought.
4.Don't lose your faith. If I can be a master, so can you. Just solve more problems and have fun.
Good luck to our cp career:)