Well, as a kid I used to collect at random, but now I actually worry about condition and attempt to complete my sets. I prefer the Japanese sets to English, and I tend to order booster boxes from Japan to complete sets... last one was Lost Link, which fortunately only had 40 cards in it, so I only had to buy one box. If it's a bigger set I sometimes have to buy two. I find booster boxes to be the most economical, especially because I can order them for relatively cheap on ebay, and because in Canada booster packs are rediculously expensive. Even Walmart sells packs for $5.50 :\ Then I got into the game a few months ago, so now I also collect cards that I would never even look twice at as a collector, stuff like Poketurn and the like. Right now, I'm trying to get a Donphan prime to complete HGSS, and I'm working on a Gyarados collection, which I'm hoping will contain all Gyarados cards including English, Japanese, 1st ed, and all holo-variations. I generally have to get those from ebay, which takes a while to complete, so I only have about 20 different ones at the moment. I would say ebay is my main source for collecting.