Offering a specific amount of free revisions is a great suggestion! First, I find that it helps some clients who are new to hiring freelancers because it lets them know it is okay to ask for a revision. Second, it puts a limit on potentially problematic clients and forces them to be clear in their communication.

However, to be fair, sometimes I do as many revisions as they need, and often the client is very happy for that. I once got a 25% tip on a small job after 6 or 7 revisions to find just the right wording.