Agree on the sanding. I always go down to 400, and apply Balsa-rite. Also I use a tool called the Wood Pecker, helps miniize air bubbles on the full sheeted surfaces. All that said, the bigger challenge is not to rush the covering. After all the time spent building its natural to want to GET IT Covered NOW. I do a little bit at a time, if Im in the groove Ill cover longer, if its not working out I turn the iron off and take a break. Im currently covering a TF GS P-47 and keep reminding myself that it will take a month so dont rush= cant fly when its snowing anyway.