I want to talk to this guy that works up the block from me... how do I make the 1st move without looking desperate?

You said in an earlier post that he works in a store and tries to get you to notice him when you go in. Next time you go in, ask him to help you find something - even if you already know where it is. Don't say "can you TELL me where such and such is". Say "can you SHOW me where such and such is"

Being a guy, I love when a girl is straightforward about things. It is very flattering when a girl says exactly what you think and builds up the confidence of both parties. A bold girl is always the best bet.