One of the biggest mistakes most agents do is they lie to their potential clients right from the beginning. They meet someone, make promises, and set up expectations that they can't possible keep up with.
One of my favorite questions from potential buyers and sellers is, "Should I wait about six months and see what happens?" Most agents tell their clients that if they had a crystal ball, they would tell them, but their opinion is that they should buy or sell now, because you don't know what the future will bring. Give your clients the facts and let them decide for themselves. If you tell them what to do, you may be setting yourself up for a lawsuit.
I tell my clients, "If I owned a crystal ball, I wouldn't be standing here because I would be at the lottery counter buying tickets!" Don't set yourself up by promising your clients things you can't possibly deliver on. I say, under promise and over deliver is the way to true success and client happiness.