painting dash

i got my dash out and have sanded the majority of the pieces smooth and are ready for painting. question is, what steps do i need to take when painting plastic so it doesnt crack, or spiderweb when i put it back in? the main portion of tha dash has to be bent a lil to get into place.and also, what kind of paints and/or additives should i use when painting the plastics?could any of yal give me product numbers of the paints i would need to buy and the brand it is? thanks