Here's a few of the ways I find them.
- Check your own followers followers - you might either find someone you already know but didn't know was on Twitter or come across someone interesting to follow.
- Look at Twitterholic and find other Tweeters in your location - town, city, area, country. Great if you're focusing on a particular location.
- Look at your Twitterstream - you'll see snippets of conversations with people you're not yet following. If they have something interesting to say, check out their Twitter profile and follow them.
- Check out the #followfriday tweets from your followers - who are they following and recommending.
Personally I'd say DON'T autofollow - you may end up following people you really have no interest or connection with or those who are just interested in numbers or have one-way traffic.
AVOID the 'get more followers' or 'find hundreds of followers' schemes - for me, they're the equivalent of junk mail. You'll get lots but how useful or interesting will it really be?