I have only been using a spinnaker with my cat for about 6 months and feel like a complete novice. It seems like every time I go out, I figure out (the hard way) what to do, or not to do. I would love to learn some of your "Do's & Don'ts".

Here are a few random ones of mine. I have a Nacra F18 with a front snuffer, so that is my perspective. Obviously, different boats or snuffer systems will have different issues.
1. When dousing the spinnaker, if I sail close to straight downwind, I almost always run over the spin sheets with the windward hull. It is really a pain to clear the lines after that. I need to be a little upwind when dousing to avoid this.
2. Rather than trying to see if the spinnaker is raised up to the proper height, I have marked my halyard so I can easily see. Because my halyard is blue, a marker would not work. Instead,I just used a needle to thread a couple pieces of sail repair thread through and tied them off. I can easily see the thread and they do not interfere with the pulleys.
3. When solo sailing and using the spinnaker, its hard to give your forward hand a rest. I have found that I can free up my forward hand for a rest or other needs by positioning the tiller extension a certain way. I put the tiller extension behind my back and hook onto it with the inside of my rear elbow. With this arrangement, I can very effectively steer by simply twisting my upper body. My rear hand can hold the spin sheet, giving my front hand a rest. Try this if your are solo sailing...it works.
4. Apparently, it is important to use your mainsheet as a backstay when sailing with a spinnaker. I think this is an important matter that should be more widely publicied than it is. I understand that its possible to damage your mast if you ignore this issue.

Here are some questions I have:
Can you trapeze when solo sailing a spinnaker? This is something I have not tried. I have trouble seeing how to secure myself to the boat during this point of sail while hanging onto the tiller extension and spin sheet only, especially with course changes necessary to react to the gusts.

How do you avoid snagging your spin when dousing? I seem to get a high percentage of snags on something during snuffing. By this, I mean not only the hull running over the sheet, but also internal snags in the sock, etc.

How do you tell if your halyard is too loose or too tight?

What's the best way to jibe a spin? There has got to be a better system than mine.

Steve