...I guess my quetion is this: if I want to get comfortable in reverse, where should I practice? I have thrown the engine in reverse on Puget Sound, but that doesn't really do much for me since I don't have any landmarks/obstacles to navigate around. I also don't really want to practice in my slip area since I am not comfortable. Also, since it is an outboard should I steer with the outboard rather than the tiller? I use the tiller when moving forward, but worry that it won't be as responsive in reverse...
Are there any public docks/piers in your area -- the type where folks can tie alongside temporarily to load/off-load passengers and gear? Or a fuel dock that doesn't get much business on weekdays? Or a ramp with a floating dock alongside? If so, try your docking practice there when no one else is around.
As for using the outboard or the tiller: I would try first to just leave the outboard locked on centerline, and steer the boat only with the tiller. Normally, a spade or transom hung rudder will work very well in reverse too.
The trick is to turn around and face aft as you're motoring in reverse. Turn the tiller so that the leading edge (while going astern, i.e. the edge that is usually the trailing edge) of the rudder is pointing in the direction that you want to go.
In other words, when facing aft and going astern, if you want the boat to turn to starboard, deflect the tiller to port. Try this out in some open but protected water. I think you will be surprised how responsive and easy it is to drive around in reverse while steering with a spade rudder.
When you try backing out of the slip, just remember that the bow will usually swing the opposite direction from the stern. So you want to back out straight initially, then cut hard when you know the bow will clear the dock pilings and other boats. Cross winds and currents may require you to counteract at times.
If you are in an especially tight spot, you may need the directed thrust of the outboard too, but that can get more complicated, so try using only the tiller at first.