It's taken me a really long time - around 6 years now I think. I reached 7k pretty fast, maybe 2 years in. Every rank after that has come very slowly. It seems like just about everyone I talk to has gotten better faster than I have, so you may not want to take my advice too seriously.

I read a lot of Go books, some help, some don't. I think the most helpful was Janice Kim's 5 book learn-to-play-go series.

I also read lots of game reviews from the Go Teaching Ladder, and do some reviews myself.

I try to play in tournaments whenever I can. I'm a very competitive person, so knowing there's a tournament coming up really gets me in the mood to read and practice.

Oh, and play a lot! I try to play every day, mostly fast games on KGS.

-sam