Clean them first and you should be good to go. If they are smaller snail shells and you have hermit crabs it is a good practice to have some empty shells anyway. If not your hermits will eventually kill a snail for its shell.
Welcome to R2R and the hobby.
Free advice: The most expensive part of this hobby is impatience. Decided what you want,save up for it if you must, get the best you can and only buy it once! Enjoy the hobby!