Narcooo let me explain you something.. i play this game for 8 months.. daily... but i am not upgrading unnecessary buildings.. i upgrade only RL, NCG, Helipad, TC and squad camp....also I research only missile, firebomb, freeze and fuegos.. sometimes smoke. Nothing else., I get so much experience for nothing.. let me show you something..
So I upgrade and build only expensive buildings.... and i haven't built 3 storages and 2 defensive weapons...
I do not intend on building that.
AND THIS IS WHAT I HAVEN'T BUILT...And I won't .. because it gives me too much exp.
I started with that method when I was lvl 40.... building only necessary buildings