when you are finishing a level for the first time, let the waves come at their own pace and dont try to get any amulets, finish the level first, THEN get the amulets. when i realized this, it helped tremendously!!!
ah, tips for causual players... hm... not necessarily. level 1, for starters: you can call all the waves fairly early, even with wizard level 1. on later levels, or if you're struggling, only call them a few frames early, so you can still get an amulet. in fact, why not..MMMMFMFFPFHF.... er, for expert tips,read some of the pages in http://armorgames.com/community/thread/3305675/all-things-gemcraft-0-here