I'm a class A player with the USCF (~1840). But in 2006 I was class D (~1300) before I started taking lessons with NM Dan Heisman.
I've been coming to this site for quite a while and I believe it has helped me to better my analysis skills. It is very insightful to read posts by some of my favorite kibitzers: <johnlspouge> (was he kidnapped?), <dzechiel>, <TheaN>, <CHESSTTCAMPS>, <agb2002>, <gofer>, and of course <Once>, and other kibitzer "greats". My appreciation goes to them for helping me reach a higher level.
My thoughts on improvement have changed recently. I used to be dead set against helpmate problems which I thought teaches you the bad habit of expecting your opponent to make a bad move. Too much of anything is bad, but this has the positive of training piece coordination which is a very powerful skill to have. Here's another example: My coach showed me a few problems where you must force immediate checkmate by swapping any two pieces on the board, resulting in a legal checkmate position. For example, you can't swap a piece and a pawn if the pawn is on the 8th rank or checks your own king--that's not a legal position. There are many ways to improve key areas in chess.
If anyone wishes to critique my analysis or ideas, feel free to do so. I won't take it personally. I need feedback! Or if you want opinions on improvement, feel free to ask.