thom i work as a promoter in nc and here's some tricks that work pretty good.....
girls get in free before 11 or 12, guys 3 dollars before 12 5 after (or whatever your charging for that matter...cheaper before 12).
Work with the bar and have drink specials end at 12.
Most headliners won't play until 12, its usually in their contracts, or at least the ones I've worked with, but you can also make locals seem like a big deal, also opening with locals that are a big deal but aren't headliners. If you make the people who are planning on showing up late feel like they'll miss something if their not there by 10 or 11, they'll start coming out early. If your taking the door and a percentage of the bar (thats the agreement I have worked out for my events) then the more expensive cover after 12 is definitely a must, and most club/bar owners will stay open pretty late if you ask them before hand meaning your still taking money from the door after 2, so ideally your more expensive cover after 12 makes up for what you miss at the bar after 2.
Anyways, hope this is of some use man. Good Luck.
