I got to level 50 in less than 2 weeks. Here's what you do:
Get 5 nesters but put 6 nests so you can move them around.
5 soldiers MAX. Also use them to repair buildings if you need b/c they only sit around.
Everyone else workers.
Put storages NEXT to the workers means less time to move= harvest faster.
Also check neoboards for gifts. Lots of people will gift you stuff, which means you level up even faster. IE. storages, nests, and stuff.
Pests usually come out if you have a lot of food left out. So later on, put lots of food out so they'll come and attack you. This means more exp.
Leave overnight-you don't have to worry about anything--unless you're cheating while doing this. But when I was legit I was still fine.
Also keep 5 soldier eggs and discard the rest until you need them. ONLY DISCARD SOLDIER EGGS. Unless you get tons of nesters. Nesters you can toss out too after 5.