bizybeehill --- I haven't read all the responses on this thread, so what I'm about to post may be redundant, and many folks may disagree, but here are a few thoughts concerning cattle auctions that are just IMHO. (And I'm really only talking here about COW auctions and not BULL auctions)
Keep in mind that there are major differences in the auctions that are held each and every week versus the "replacement" sales that are held maybe twice per year in most areas (and sometimes dispersal sales). While it would perhaps be interesting to you (and instructional) to attend a few weekly auctions, I would say to remove from your mind any notion of buying stock at the weekly events --- at least until you have a lot more experienced.
But do go to some of the "replacement" sales, as many as your schedule permits. Get there very early the day of sale (or even go the day before), get a copy of the sale catalogue and then start walking around the barn and inspect the animals with as critical an eye as you can. Jot down notes on the catalogue for anything you think may be of consequence, such as apparent disposition, color, polled or horned, body condition, etc. The catalogue typically shows the breed, age, number of months bred if applicable, breed of bull to which bred, name of the seller, etc. Then assign your ranking to each animal, say #1 for highest , etc. on down to say #5 for least desirable. Then, during the first few auctions you attend plan on "sitting on your hands". Closely observe the auctioneer's methods and the crowd action (I like to sit high and way in the back) and mark down on your catalogue the final bid price for each animal. Based on the final price and the bidder action you can get a decent feel for how the other presumably more experienced buyers essentially rated the animals, as compared to your ratings, and learn from that.
A "mentor" that has a lot of experience would of course be a great asset to have. Ask questions (without making a pest of yourself) of your mentor, and try to get him to critique some of the animals for you.