@wornslick good luck getting anything for less than greysheet from Heritage. Their niche isn't wholesale, it's desirable high-value coins.
@KenKat Best way to bid and win is to bid more than anyone else. Yeah, that sounds like a stupid answer, but if you're looking for a way to game the system, forget it. Unless you're looking for stuff that's really not in demand, any given item will have enough of a following that you're not likely to win for way below what it's worth. As far as bidding when there's also a floor auction, no, it's not pointless, you just have more competition bidding against you (and competition that has a huge advantage on you - they were able to view the coins in person).
With all that said, although I've followed a few of their auctions, I've not bid. Most of their stuff is way out of my price range for one, and for two, they're in Texas, which means having to pay sales tax, which would immediately put me at an 8% disadvantage to other bidders.