On glass areas like side windows and Opensky here's what I do:
Clean thoroughly.
Clay as you would normal bodywork, using a light compund such as Meguairs QuikClay.
Use a synthetic sealant such as Jeffs
Doing this guarantees you an "as-new" finish and as long as you don't go overboard with the sealant clarity will be great with awesome water beading and runoff. As it's glass and not paintwork where you would be looking to build up successive coats, you can clay almost as often as you like.