If they are a few days old I would suggest using some towels. If the brooder is larger use only a light layer of wood chips. Dont use anything too slippery for the baby chicks.
For my stardard sized chicks, I used 5-6" of pice shavings - then switched out to aspin shavings that seemed less dusty and I think smells better.
For my banties, I used the wood pellets 5-6". LOVED the pellets so much better. They dry out the poo in minutes. Easy to scoop out the dried poo with a spoon.
I will forever use the pellets in the brooder.
In the big coop, I use a deep litter of Aspin shavings, wood pellets and Stall Dry.