I am an hobbyist who is making a monster truck cake for my son's birthday. His favorite truck has flames on it, but I don't know how to properly do that. Can I just paint them on with gel color? Any help will be greatly appreciated

Yes, you can paint them on if you mix a little vanilla or vodka with a gel color.

At Michael's they have frosting/coloring that is like a spray paint, maybe you could make a stencil and spray it on?

Checkout my guitar cake, I cut flames out of yellow fondant, then I bought a can of red color mist by wilton and sprayed the edges. Be careful when you place it on the cake, it will be wet and it will smuge. (is that how you spell that? LOL). I was happy with the way it came out. Good luck, Eva

Just a suggestion, I made flames using Wilton Mist Sprays from any store that carries them. Here on CC there is a wonderful template:

http://www.cakecentral.com/cake-photo_1374710.html

Here is a picture of a cake where I used this template cut out of plastic sheet cutting boards or clean sheet white card stock.

http://www.cakecentral.com/cake-photo_1733163.html.

I sprayed the template placed on side of cake first with blue, then removed the template and sprayed lightly with red. HTH
Hamsquad

Thanks for all the tips. Wish me luck!