Damn, we used to have this thread in the archives by Nomas. He explained this perfectly. The gist is that, when expressing interest to someone, you want to do it in a way that doesn't get too far ahead of their interest level. You show interest, they respond. You show a bit more... they respond. If not, then you wait, then check their interest and try again. And so on.
Its like heating up a glass... do it slowly a little bit at at time and you'll eventually get a nice, hot glass . Do it too fast and the glass will crack. Sorry, thats the best analogy I can come up with. Nomas' was much better.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh