By Mike King
I hop the best with my left foot forward, but I also hop with right forward, just not as well or as often. I think it is actually best if you approach on an angle and have your outward pedal forward so that your inside pedal has more clearance as you jump up.
For the take off, it is great when your pedals are already in a nice horizontal position but this does not always happen. If your pedals are in the vertical position there are a couple of alternatives. First, if its a smaller hop you should be able to from any pedal position. I learned this by forcing myself to hop curbs straight on so that my pedals where often verticle.
Or, I often stop with my pedals horizontal and just hop myself closer to the object I'm jumping on. Then when I'm in position I do the bigger hop. I find though that I can jump a lot higher when I'm rolling toward an object and then jump onto it. I think this method lets me bend down forwards more and tilt the uni forward as well so that I get higher and then I use my momemtum to continue over the object.
With lots of practice, you will start to learn to twist during your approach to compensate your peddle positions and make them aligned correctly for when you get to the object. I seem to just do this naturally now since I'm riding so much.
I think an important factor for hopping is the seat height. The lower the seat, the more room you have to spring with your legs and the higher you can jump. I have lowered my seat three inches before and I could suddenly hop 6 inches higher!
So in general, aside from simply practicing, try these tips if your learning to hop and good luck with it. It is an awesome skill that is essential for mountain unicycling.