My belief to doing pick 3 & 4 lotto is

1. Look at the previous draw and two. Recognize the type of pairs. See if doubles are due2.. find main key for next draw. Without a key, i don't know how you can just pick a number
3. firgure pairs/triplets
3. find x= 0 to 9 or x=any nbr
4. organize it in boxed or str8 form