Who should I follow on Twitter?

It is tempting at first to follow anyone you come across, but that strategy can quickly backfire. I would recommend  following only people who are worth following, these don’t have to be people you know personally, but they should meet the following criteria:
when looking back on their posts, make sure they are of quality and content you would like to read in the future
they are respectable individuals, you don’t want to follow sleazy sales, haters, vulgar, or otherwise obnoxious people
follow trend-setters in your area of interest, you want to be the first informed person who “finds” and re-tweet some groundbreaking news
key people to whom our post may provide value
if you are attending a conference follow all participants, you never know who you are going to meet, a week after the conference you can do some cleaning up

Uki's Google Java Technology blog