RE: Rubs and Scrapes
Cord, deer make rubs well in advance of the rut, they use it start strengthening their neck muscles for the up coming mating season. Scrapes will start before rut too, but long after you start see rubs. You'll often see V-type scrapes once the bach. groups start to dispate and then the big scrapes are laid down. However IMO and experience scrapes don't produce the results like the rublines do, so I really hunt the rublines.
Yes, scrapes are on the ground and rub on the trees. What Jimpic was saying is primary or active scrapes have a licking branch above them, this where the buck will chew on and leave more scent. He also was saying, generally that the bigger bucks need a bigger tree to work their neck muscles. While it is true large dominant bucks hit the saplings, they will also need those larger based trees (if available) to further prove their dominance. So look for trashed areas of saplings, broken branches (especially up high) and him tackling the larger trees as well...then you know their is a big boy in the area. Another key is how high the rubs are up the tree, sometimes you'll see nice sized rubs down low, that doesn't mean he's big, but if you see it graduate upwards of the tree. Like Jimpic said, many deer will frequent rubs, so don't be put off or discouraged when a small immature buck appears and what seems to be a great large buck rubline or scrape. They will all inhabit the same area and instictively they do these rituals to prepare for their turn.
This is something that you will learn with practice, it's no different than rattling and calling. You need to experience it and learn, pointers and basics from others help in the learning curve, so don't be affraid to ask.