What powered skills translate best to glider?

My recomendation is to spend as much time as possible preparing for and passing the written exam. Your flight sessions will be much more productive if you understand the theory before you get in the cockpit. Any flight time you can get is benifical including condor, but make the most of each opportunity by being proactive. Read as much as possible. Fly the real thing on the weekend. After you have passed the written, if you are not satisfied with your progress in the club, take a vacation to some place like Estrella Sailport. There you can fly twice a day for a week or so. Be prepared however for a big price tag. The club can be frustrating in the begining. Don't give up, stay with it.

Jim