hang out at the club you want to play at. Listen to what the djs play at different times, what the crowd likes/doesnt likes. Meet the owners, regulars, promoters and djs, also make yourself known. Sending out mixtapes to promoters will do nothing, you have to show them you like the event and support it. Be patient and make sure you are more than ready for your first gig (even if you think you are, you arent)