i use crayola cos they're toxic free, made in european countries or USA, where there are quite rigorous tests on children's toys, so i trust them.
when i let my daughter play w/ crayons, i'm always there to play with her (or someone responsible is), & literally keep my eyes on the crayon, so when she wants to put it in her mouth, someone is there to stop her & say "no" firmly). i think they need close supervision when they're playing with things that they can put in their mouth before 3 yr old. ditto play doh
there are washable crayons available at toysrus, so if she draws on her clothes, the carpet, anywhere, it can be washed off. plus i open a big mat, for us to sit on, so she won't be drawing on the carpet. i started giving play doh & crayons to her when she was about 13 mths. she's now 19 mths & every time she wants to play with play doh or coloring book, she says "mat", before she go gets the doh/crayons.