These are some of my favorite subreddits:

http://reddit.com/r/hiphopheads

http://reddit.com/r/frugalmalefashion

http://reddit.com/r/javascript/

http://reddit.com/r/snowboarding/

I find these subs to be on topic, relatively positive, often receptive to the new and uninitiated, providing a wealth of FAQ/just starting out information and have interesting weekly events.

I especially enjoy the header with album release dates in hiphopheads, and there are a number of cool weekly events in frugalmalefashion (and its more expensive brother subreddit, http://reddit.com/r/malefashionadvice).

As with any sufficiently large group, you'll find groupthink. However, I've found that many smaller subreddits are more receptive of self-criticism when it gets too bad.