Practice setting and dousing while tied to a dock. Orient the boat facing downwind, it helps if the boat can move a little from side to side. With it secure you can go through your learning steps with no fear. You can practice setting up the pole, rigging the sail. Your team can practice setting, gybing and dousing in relative safety until they feel confident enough to try it on a light air, small sea day. Then you'll be comfortable enough to concentrate on trimming and tactics and the other fun stuff. You really want at least 2 others to know what's going on. And you need everyone to do everything... that means you also need to work the foredeck and as part of the afterguard. You'll want to know which jobs you can assign to newbies and which jobs require your experienced people. Everyone needs to know how to steer the boat, they need to know how to get the sail down, they need to know how to re pack the sail so it can be used again.
Spinnaker sailing is very exciting and it is a great team building experience. The sailing school I went through at San Diego State culminated in a J-24 class series, where we sailed as a crew of 5 or 6, out in the ocean off Pacific Beach. Way back then we had 4 boats in the fleet and often had opportunities to race each other. The spinnaker sections of the race were the most intense and, by far, the most satisfying. After those classes, I was hooked, and even though I loved racing my Laser and later on my Nacra 5.2, I always found time to sail beer cans on the larger boats and their colorful spinnakers.
John Rousmaniere's "Annapolis Book of Seamanship" was also put out as a video series and has a lengthy segment on symmetrical spinnakers. It's only on a 21 ft Sonar, and it's just him and his 12 year old nephew he's teaching. But... I learned so much watching it I could recommend it. There are a number of YouTube vids.... watch them all. They're free.
