Hmm my top five must haves when I started:
-adhesive (both liquid and tape). I started with scotch quick dry and scotch permenant double sided tape-both available at places like walmart
-papers (patterned and cardstock-i'd suggest a variety pack of CS and a paper pack like DCWV)
-a corner rounder punch-EK success makes one that can also be used to make scalloped edges. It is a way to try punches without investing too much.