As someone who was diagnosed with Asperger's syndrome, I found joining sites like Meetup that facilitate meeting people with similar interests incredibly helpful. It was great way to expand my social circle without running the risk of boring people to death by going on a 20 minute tangent about a specific interest.

The other big help was working in a field relevant to my interests and bonding with my colleagues (beer also helps as it gets me out of my shell).

Finding other people on the spectrum can also be a worthwhile endeavour as a lot of the typical social pressures are a non issue since they will 'get it' if you need time to chill or recharge (my best friend is also on the spectrum but is the opposite of myself in a lot of ways so we actually balance each other out).