A friend of mine is an airmile magician. He knows the travel reward systems so well he manages to pull off some incredible and amazing can't believe it's possible trips. when I asked him how he learns and keeps up to date, he mentioned the FlyerTalk forums.
As a traveller, after reading review sites (link), your next step is to sign up for and use the various travel discussion forums. On them you can learn tips and tricks (for travel clubs, hidden menu items at restaurants, little known activities to do while travelling, etc).
There are already millions of questions answered but just in case, you will also likely find someone who can answer your specific questions. There are dozens of sites but your time is best spent on the bigger ones. Make sure you join a site aligned with you (Fodors is for the older more affluent crowd while Lonely Planet is for the young backpacking student).
Forums I recommend you consider are: