I paper my balsa fins with any kind of copy-machine paper or card stock that I can find.
I cut and sand the fins (no escaping that part of the work) including whatever airfoil shape I want to use.
Fold the paper in a sharp crease---this fold will go onto the leading edge of the fin.
Pre-cut the paper, and cut it oversize so it extends past all the other edges of the fin.
I use white glue cut 50/50 with water, and spread it onto both sides of the fin with my finger until the fin is wet from root to tip and front edge to back.
Then wrap the paper around the fin, layer the thing top & bottom with waxed paper, and put it in the bottom of an old phone book overnight.
When dry, you can cut the excess paper off the root and tip and trailing edge with a straight edge and an X-acto knife. I do a little touch-up sanding with fine sandpaper, and then use CA on the edges I cut.
I seldom get any bubbles in the finished paper using this approach, and don't know what everyone else is doing that causes them so much trouble.
I can consistently get a decent surface finish and especially a nice smooth leading edge.
After all this, I glue them onto the model just like normal, and fillet.