If at all possible try to get out there on Friday or at least very early Saturday. That's alot of cattle to sort through, and they are spread out in big traps - it takes awhile to sort through them. Sometime Saturday morning the "top end" of the bred heifers will be sorted up into smaller pens closer up, making it easier to look if these are what you're planning on buying, but you'll need deep pockets on those. The other bred heifers will be kind of sorted by breed/color, making it a little easier if you're after something specific.
Wear comfortable shoes/boots, and cool comfortable clothes - it's usually warm (sometimes hot) and windy. Bringing your own chairs isn't a bad idea - the bleachers fill up fast, and outside of that, seating is pretty much on bales of hay. There'll be plenty of good food and cold drinks, so no worries there. Unless you're only intersted in the featured lots that sell early, be prepared to hang around awhile - there are always some good deals to be had, but patience is a must unless you have the money to buy what you want early.
You'll see a great set of cattle (and people). Good luck.