tigerflame my advice is just approach and lots of it your at a music festival where there are lots of people who are in a much better more social state than usual and you will most probably never see them again.

So approach as much as possible try openers or be natural and say things like hi i'm tigerflame or I thought you looked cute I had to meet you or I choose you. Just try anything use it as an experiment people are going to be happier and more responsive.
Try and think of openers while you are there, usually I think of the perfect opener after my chance has gone but at a music festival you can probably use that opener again quite easily.

Just open alot then you will get in the flow, it might feel impossible at the time but keep forcing yourself to no matter what the outcome for about 20 minutes and then you will be in full flow, open the first set you see even if it's guys just to get you in that talkative state instead of in your head wondering what you should say.

Good luck! Tell us how it goes, even if it doesn't go as well as you hoped we can still help and iron out any problems.

Remember you are the coolest mutha fucker on the planet!