For routine procedures, I always bring food. I will often distract them with a piece of food while blood is being drawn or a vaccination is being given. If it is not a problem, I will often bring an extra dog or 2 just so the extra dogs can have a good experience of eating treats in the waiting and exam rooms without being poked or prodded.
With Riley, she was not allowed to have food prior to being sedated so I brought along some squeaky toys. She was dying to play with them all morning, but I kept them put away until she was at the vet office. The toys helped to pass the time in the exam room.
I also always bring a comfortable fleece pad for my patient to relax on. Even if your dog typically stands the entire time, a pad to lay on encourages them to lie down.
If you are petting your dog during a vet visit, you want to make sure you do it in a helpful way and in a manner that encourages relaxation. Long, slow, smooth strokes over the whole body and down a leg (alternating legs). Slowly and softly stroking the ears is also good. If you are not paying attention to what you are doing, you may find that you are quickly rubbing your dog's skin back and forth mindlessly. The short, rapid, continuous strokes can increase the nervousness of the patient. Your hound is better off not being touched if you cannot do it in a thoughtful and relaxing manner.
Lastly, you may want to save uncomfortable procedures (such as microchipping) for the next time your dog is being sedated if a surgery or a teeth cleaning is coming up.