I know this is cliche, but I think the single most effective way to improve is to play a lot, then review your games with a player that is stronger than you and have them point out better moves you could have made, explain your thought process, etc. If you don't have a stronger player available to look at your games (I can look at a few :) ), then just replay them yourself, look for moves where the game turned towards one player and things you could have done better. Or, plug them into a computer program and see what moves the computer suggests, and then ask yourself why the computer is suggesting them.

For books, I started out by reading a few books by Yasser Seirawan. Two titles I particularly found helpful are "Winning Chess Strategies" and "Winning Chess Tactics". Seirawan is a good writer and both titles do a really good job explaining their concepts to players new to the game. Jeremy Silman wrote a book called "The Amateur's Mind" which I thought was pretty good, that compares thought processes between amateurs, intermediate, and expert level players across similar positions.

One other idea is to simply get a book that is a collection of annotated master/grandmaster games, set up a board, make some coffee, and replay through them. Review the authors notes. Replay them again. Get a sense for the openings being used and the different strategies. Two good collections are "The Mammoth Book of Greatest Chess Games" by Burgess and "The Most Instructive Chess Games Played" (can't remember author).

Chess.com is a great free place to play. They have free tournaments and games online, you can get a rating, track your progress, etc. If you do a paid membership, you get access to videos, tutorials etc. I just use the free membership, so I can't comment as to how good these videos are, but at least to me they look solid.

Good luck. Happy to help more offline (maybe trade for poker tips :) )