How can you tell if a girl likes you?

give me some hints please on how to tell,im clueless.what are the things they do on the internet,say.i know its different then in person,but i dont seem to know those signs either.im not a youngster im in my mid 30's.i have a myspace,but does that work or is it a waste of time.cause ive gotten no one even interested in me on it,except for a few friends,who rule by the way.