>Lesbians? How did you meet your hookups?

Simple,... check on the web for meeting sites dedicated to lesbians. You'll find enough diversity to suit your tastes.

Otherwise just hit the lesbian bars/clubs/organisations in your town.

>How did you know they were into you/gay?

Someone once told me it was enough to see the stare and bodylanguage of the other person, but I don't think it works for everybody.