Hmm, given the number of times you want to paint, I would double the amount for safety’s sake (if you can afford it!) You’re probably fine, (A little make-up can go a long way) but you wouldn’t want to find yourself short at the last minute either. If it were me, I would double.
Shore! I love answering questions. First off, you’ve picked a tough colour, Yellow is a very transparent colour, so often it tends to go on streaky or with mediocre coverage. Luckily with Flame Princess, you probably don’t want to be YELLLOOOOW. You want to have a sort of yellow tint. I’d always recommend going about a shade lighter then you think you need to be. It’s easy to go too dark with body paint and it always looks odd. Air on the conservative side.
Firstly, I’d recommend trying to find a local costume or theatre shop. I’m lucky to have a fantastic, locally owned, high quality costume shop, Display and Costume, (Shop local my friends!) in the area. These shops will often have knowledgeable staff and will allow you to test make-up products before purchase, which is invaluable to getting the right make-up for the job.
If you’re not so lucky, go with this. Buy three Ben Nye Creme Liners (these bad boys). I’ve been told the best mix is two Goldenrod, one Red. Take Both of the Goldenrod and 1/4 to 1/3 of the red (depending on how orange you wanna be). Take the lids off, and microwave ‘em for a few seconds at a time until they’re soft but not melted. Mix ‘em all together (both yellows and however much red you decide on) in a container with a stirring stick until you get the shade you want! You’ll have to wait about a day or so for them to set, so that you can use them. After you’re done mixing, I’d recommend trying to gloop them back into the original containers, just for the sake of ease. Also, if you want to save some money, save just a tiny bit of the original goldenrod yellow. Set it aside and don’t mix it in.
For application: Make sure you have makeup sponges. They are cheap as balls. Get a ton of ‘em. If you really want the makeup to look good, use the sponge to put some of this stuff on first. It sets your skin so that the makeup sticks to it better. Then, take a SPONGE (Not your fingers. Not a brush.) and DAB, don’t wipe, the makeup on. If you wipe, it comes out all kinds of streaky and weird. dabbing it on keeps it nice and even. Once you’re covered, take that little bit of left-over goldenrod yellow and fill in your lowlights (sides of your nose, cheek bones, temples, etc.) Dab on a spot of the darker yellow, then with a clean sponge, blend it in. This will just add some more texture to your face. Also fill in your eyebrows with an eyebrow pencil or something so they don’t look like they’re buried under paint. Same with the lips.
Then, and most, most, MOST important, seal it. I use Ben Nye Final Seal. It’s blue stuff that comes in little spray bottles. It is crucial to keeping paint on your face and off of everything else (particularly if you’re painting your hands). Just follow the instructions, have someone else spray it on you, and have them keep at least a foot away from your skin. Be extra careful when spraying the face, keep your eyes tightly shut until it stops tingling (about a minute). It’s alcohol based so it can really hurt if it gets into your peepers. Go crazy with this stuff, spray it everywhere.
Lastly, this makeup is gonna take some time to put on, so be sure to budget in enough time to do it on the morning of the con!
And have massive amounts of fun! Cosplay is all about experimentation, creativity and it’s always a learning process. There has never been a year where I didn’t learn something new, and find something I could have done better. You’re going to be awesome and I hope you post many pictures! Cheers!
(And sorry for the Wall-o-Text!)