The higher the Tier the stronger you'll be. Eventually you will need to get stronger roommates to increase your plunder; the sooner the better but it's up to you. The tiers are:
OP-Original Poster (author of a thread) or
Over-Priced (as in, an over-priced tutor)
Scavenger hunt items are randomly dropped, so it's really luck of the draw as to which items you will get from parties. Some people get 1-4 items, while others may not get any