There are two very different approaches to festival make up.
One is the approach taken by girls at their first festival - bring all of your make up in a giant bag, put it all on for the first day, then leave it in your tent to get stolen/melted/washed away in a biblical flood/pissed on and never bring make up to a festival again.
The other is taken by girls in their mid-twenties that probably shouldn't be going to festivals anyway but thanks to the likes of La Moss (grrr) and the fact that they look like crap without it, are forced to wear tactical slap.
That, my friends, is called a run on sentence.
Tactical slap isn't the same as nude or no make up make up. You clearly want people to know that it's there but that you threw it on in a devil may care, I'm so too good for Pete the smackhead Doherty kind of a way. I recommend the following:
Tinted moisturiser and concealer to help you out the morning after. BeneFit It Stick comes as a pencil so is super portable and cover a multitude of sins (but not that dog you picked up during Razorlight and found in your tent this morning. Only forgivable if you had to find something to take your mind off Razorlight)
Give powder a miss and, if you must mattify, go for MAC blotting papers or BeneFit Mr Feelgood balm. No one is fooled by a pasty, powdery face when you're living in a tent.
Mascara is controversial. I would suggest tinting your eyelashes with Colorsport 30 Day Mascara and avoid facing the potential mascara in the eye/how do I get rid of panda eyes with babywipes debacle.
Multipurpose colour is essential. I love the new Bobbi Brown Stonewashed Pink Rouge Pot, shown here with the matching gloss and lipstick. It's a gorgeous tawny pink that sits somewhere between a blusher and a bronzer but gives a healthy hit of colour to you cheeks, lips and lids. Winner.
Shitloads of it.
My friend swears by Bad Gal and maintains annually that it just looks better and better if you sleep in it and touch up the next day. As a contact lens wearer, I do not recommend this but it really is the definition of festival make up. Eyeliner is dramatic but says, 'yeah, I tried but not for you'. It's pencil on attitude plus it takes attention away from how rank you're probably looking in general...
I'm thinking about rocking some colours as well as traditional black - maybe even some Urban Decay Heavy Metal glitter liner or their glittery Pocket Rocket pencils.
What I don't recommend you try is an Amy Winehouse liquid liner look in a tent unless you're a) a Geldof and staying in a sponsored RV (cow) or b) Amy Winehouse and I'm guessing even her handiwork has been a little shaky lately.