Arbiter's tactic is TCR. (Btw, If you know graduates, you can ask us too.)
For the next step, NALP and http://www.chambersassociate.com/Search/FirmList
were my go-to places to start researching more about where firms have offices, how big their summer classes are, permanent offer rates, practice area strengths, etc. Some of those things are good to know for making your bid list; others become more important once you get your screeners.
Summer class size and number of slots at AJF (or whatever other job fairs you are doing) are, in my opinion, key, but for slightly different reasons. Number of slots is important for bidding: I didn't get a slot with one of my #1 bids because they only has 20 screeners and more than 20 people bid them #1, so it ended up being a totally wasted bid. Class size is important for getting offers. Firms with smaller class sizes can sometimes be a bit pickier. By picky I don't mean more grade-selective, but that within their target grade spectrum, they might give fewer callbacks than bigger firms. Also, such firms will sometimes end up not giving offers to anyone at Cornell simply because they only have 10 SAs and interview at more than 10 schools. (One firm I know of gave CBs to three people in my class and gave offers to none.)
I would also, especially if your grades aren't where you'd like them to be, research firms that are not
coming to AJF and make a list of them so you can mail applications to them separately. This can be especially valuable if you have ties to a secondary market that typically doesn't recruit heavily from Cornell.