Learning Modern Correspondence Chess (Online or Turn-Based Chess)
I miss being able to play a slow game of chess under straight OTB rules, but I rarely have the block of time necessary to sit down and play a slow game, either online or OTB. So, I've come to accept correspondence chess as an alternative and have learned that it has its own particular charm.
I learned more chess more rapidly when I began taking Chess.com's Online or Turn-Based chess (i.e., modern correspondence chess) very seriously. The analytical opportunities are tremendous, especially if you play just a few games at a time and delve into each position as you go.
While the Analysis Board that Chess.com provides with your games is good, it cannot compare with an analysis board that will save all of the lines of play that you investigate. This enables you to do your analyses without constantly having to go back and say, "How does that line go again?" They're all saved right there (with your own comments) and they're all replayable. From any given board position, you enter all your candidate moves, investigate and save different lines of play from each, and then select your move. (No chess engine or tablebase is involved, of course.) I'm a Mac person so I use ExaChess for this. (See photo insert.) Since correspondence-style chess allows you to use books and databases, like Chess.com's own Game Explorer, you learn from them as you play.
After each game, be sure you analyze it, with Chess.com's Computer Analysis feature and/or your own computer, especially the games you lose. Studying your own lost games is extremely important to improvement. One of the advantages of Premium Membership is that Chess.com will analyze more of your games for you and with a higher-rated computer. Platinum members get up to 25 analyses per week at GM analysis level; Diamond members get up to 100. Caveat: Use Chess.com's Computer Analysis to check for gross errors, but do not expect it to give you accurate suggested lines of play more than a few plies deep. (See http://www.chess.com/forum/view/help-support/am-i-reading-this-chesscom-computer-analysis-correctly.)
I'm a big fan of Chess.com's Tactics Trainer and Chess Mentor, both of which I know have been responsible for a lot of my improvement. A Diamond member gets unlimited use of both of these great tools, as well as Computer Workout, so if you can figure a way to afford a Diamond membership (like maybe for your birthday?), I say get it.
I still miss slow OTB games, though.