Re: asa school vs buying own 20-30ft and teach self?
Buy a boat, something you sit 'in' not 'on' and get someone to come out with you to show you how to hang the rags on the sticks.
Go sailing until you are comfortable then get a racer to come out with you and show you how to use the spinnaker if you have one and how to get the best out of your sails. Even better if it is preparation for an evening 'beer can' race. Everybody should do a race at least once, some will get the bug and others will say once is enough.
Sailing is 99+% common sense. Mind you there will be a time you need to know what to do and to do it in a hurry.