I suggest resining a test piece or piece you wouldn't mind re-doing so you get the feel of the time length you have. When you start your helmet, putting it on a stand helps a lot. I used one of those long boxes of soda cans with a big a jar on the inside to weigh it down. Resining by sections is also recommended and adjust the harder drops depending on the climate where you live. I decrease the drops of hardener since Hawaii's temperature almost always stays in the 80's. If you use plastic cups, double up on them or use foil to line it. Using the same mixing stick might not be a good idea as it could cause the new batch to harden faster. Aaaand finally safety gear! A respirator with organic filters and gloves (lots and lots of gloves if you're messy like me 'cause the resin gets sticky fast).
If you got resin on you, acetone or nail polish remover works wonders, though you might ruin your manicure. ): You got patience I'm jealous for! Keep up the great work!