People will follow you before long. Here's my strategy for deciding who to follow back: when anyone follows me, I look at the first page of their tweets. If I find something particularly useful to me, I follow them. If not, I don't. Occasionally, I'll make an exception for someone just getting started when I (1) know them, and (2) know that they'll be offering something of value in the future, even if they have very few tweets now. But there are a ton of dubious marketers out there who will follow everyone they can find, hoping those people will follow them out of courtesy and they'll develop a following that way to whom they can sell whatever it is they sell. They are a complete waste of time. Concentrate on people whose ideas are useful to you.