If I've taken an undergrad Sipser-based theory course, and that's basically the extent of my knowledge, what tags should I follow to maximize the number of questions I can meaningfully answer on this site?
How about some of these:
A couple of caveats:
As the most popular tag cc.complexity-theory gets about 1 question a day, compared to large sites like Math.StackExchange and Stack Overflow there is less of a need to follow only particular tags.
The level of questions may be somewhat high as the site is for theoretical computer scientists and researchers in related fields.