I pretty much always sail alone. After my first solo sail I almost prefer to sail solo. When I do have company on board I give them the option of being crew or passenger, and to be honest I hope they pick being passenger.
My biggest precaution sailing solo is wind speed and reefing sooner than later. I normally get a quick buoy report from a few locals and set a reef at the dock if need be...
Addict makes a good point that I forgot- It's far easier to put a reef in at the dock, than it is to put one in while you're single handing. If the breeze gets light, you can always shake it out, but putting it in alone is harder.