[tmallen]

Read Nimzowitsch's "My System": https://en.wikipedia.org/wiki/My_System

Everything you need is in that book. It's not too long, and very readable. It has a very common-sense approach. Look for the 21st century edition at used book stores or your chess club: http://www.amazon.com/My-System-21st-Century-Edition/dp/1880...

chesstempo.com is good for practicing tactics between games.

[adamconroy]

Umm. 'My system' is worth reading but only so you have an understanding of what you are unlearning as you get stronger. In this day and age it is a long way from all you need to know, chess is much less dogmatic and more objective. The demands of the position trumps nimzowitsch's rules.