Reduce Reuse Recycle
, your tricks that is. But make sure to remember faces as to not show the same trick twice for a largely the same group. Make sure also not to have 4 tricks, you need enough tricks so that you don't hear "oh thats a good one, he did that on me" from every single group.
Make sure that you always have a few tricks that you don't show in case they pin you down for more (and make sure to let them know its the last few you will do), and those should be some of your best ones. If they don't pin you down you can just save them up until a very good opportunity (like for the guy who is paying you). Because you don't want to say "I don't know any more", or even worse try to do really lame ones or ones you are still learning.
Make sure that you know exactly which tricks you will do, practice them, and don't forget to do them. Write down their names, and if thats not enough then write down a basic description to jar your memory.
Take the drunkenness of the average person in the audience into account. It's all about maximizing the experience. You don't want to do simplistic tricks on sober people, and you don't want to do complicated tricks on drunk people. It's a balance.
Act natural, just like you are one of them. If you see a few people talking about something, walk up to them and sit in on the conversation. Maybe let them see you shuffle fancy-like until they ask if you're "the guy who does the card tricks". Do not rudely interrupt groups with "hey want to see something?". It's all about being casual.
I find that when I'm doing tricks for slightly drunk people it is crucial to have a light attitude. Do not try to be like these kids on youtube with them tigers and them technoes and black clothes. You want to have a smile, make a few jokes, be amazed at your own effects, and make sure to give them time to enjoy the trick.
This is a hot tip
, spot out easily impressed people and/or people that might actually believe in magical things and do tricks for them while they're in a group. The best thing you can do is find somebody who will think you are making magic with your fingers and yell very loudly anytime you do something. I think that seeing a person be excited brings more excitement to the other people in the group, _especially_ if they know each other. I find that the easily excitable people are usually girls. Look for religious artifacts, thats pretty much a must (don't see too many atheists believing in magic).
And lastly, make sure that you know exactly what the person who hired you wants. They clearly thought about hiring you before doing so. Ask them what the reason is, and what are their expectations. I think you can't go wrong doing that.