look at what you already have and find that thing(s) that makes you really excited. what particular qualities about this make you feel this way? is it a character, a color, a material, or the overall weight and shape and size of the thing? go in that direction and find what you want to get more and more and more of. though i am not really a collector of anything specific myself, (i do love sanrio goods) everything i buy—whether it be clothes, home goods, art, etc—has to absolutely have the qualities (color, proportion, weight, overall look) that i have examined and discovered are really important to me.