Small eggs are relative to the breed. If you hatch a silkie out of a small egg is different than a large breed out of a small egg. Some people hatch pullet eggs though, so it can be done.
If you see a hairline crack, don't use it. It can let bacteria in the egg.
Okay then. Pick clean ones, no cracks. Don't wash them. Store them in an egg carton and tip the edge of the carton once a day until you have everything you want to hatch collected. Put them all in at the same time.
Well first off, choose the kinds of chickens you want to have. What do you like? (examples....blue chickens, colored eggs, etc)
2nd.....Don't go too expensive for your first run of your bator.
3rd..... take into consideration your climate. Breeds with large combs can be sensitive to frostbite...