Plan to check your traps at least every four days. Leaving a pot in longer just makes it more probable that the bigger ones will eat the smaller ones. Look around and see where others are placing their pots. You don't need to be right in among 'em, and maybe it would be a lot better if you found a similar place with less competition. Try to understand why others are fishing there.
Lobsters hide in the edges of grass banks and forage at night.
Look for deep channels near shallow grass. Put your trap right on the edge of the deep water. Give it a couple of 4-day cycles before you give up and move it. Sometimes a short move of only 30 feet will produce nicely. If one pot catches and the others don't, you can group a few pots around that spot, but try to understand why they are there.