It took me a while to come up with an answer for this one. The best advice is easy because I listened and used it, but the worst advice took a while because I discard stupid stuff and forget about it. I did finally think of something.
Best Advice: "Break things down into small pieces!" I am goal oriented, but I get so hung up on the final big picture that I lose the details sometimes (other times I can get so caught up in details I get nowhere). Clicker training has helped me a LOT with breaking things down for the horse and for myself! It saves us both a lot of confusion and frustration. It's also a great way to make sure there are no holes in my basics. :D
Worst Advice: "Teach a foal how to lead by putting a halter and lead on it, then tying the lead to the saddle horn while you ride the mother around, dragging the foal by it's head".... yeah that's not advice I'll ever use!!!!