Have a really good look at the animals forward, in their pens before the auction starts. You can get into the pen and handle the animal gently, so you can check mouth, feet, genitals, check a ewe isn't a wether, etc and check for ease of handling v wildness. Take a note of the lot number and the order in which the sheep are being sold.
If possible, listen in well before your choices come up, to get your 'ear' in - auctioneers are a bit difficult to hear and understand. You will also get some idea of the range of prices on that day.
I tend not to wave frantically, just lift my card where the auctioneer or his spotter can see you and your bidding number, and maybe flap it around a bit til you're clocked. Once you've caught his attention, you just need to maintain eye contact and nod when necessary, without dithering if poss.
If bidding reaches your max, then drop your eyes, drop your card out of sight and shake your head 'no' when he looks for your next bid.
If you win the bidding, then hold your card up so the spotter can take a note of it.
I never make the first bid - often the auctioneer will start high and quickly drop down to what he intended to be the starting point anyway
If there are several folk already bidding then I let them do the initial work and I only start bidding once they start to drop out. You have to be on your toes though.
I try to keep in mind that there are plenty of similar sheep on offer, so I don't go over my max, unless there's an animal I absolutely have to have no matter the price, in which case I just keep bidding confidently and promptly til the other person chickens out