First focus on Beating Anakim six times to unlock Paradise lost, then focus on beating Gabriel. It is in your best interest to attempt to beat these maps without taking damage at least once, though these will not be crucial to efficiently unlocking the 48 achievements. At this point you should have unlocked a large number of achievements from being the reincarnation of Robin Hood that I know you were born to be as many achievements are unlocked purely from killing a certain number of enemies. As you unlock and discover trick arrows be sure to use them liberally besides whatever set you play to keep for the bosses. Each Trick Shot has its own achievement based on use.