Papering and Sanding: How much?

Building my Ventris (and I haven't really made enough progress to start a build thread on it, but if people liked my last one, then maybe?) and I decided to try papering the fins. I have no doubt that the plywood will work just fine up to anything I throw at the rocket -- I've heard of people using the cardboard PSII kits well into H territory -- it's mostly because it seems like it should save me time and effort with sealing and finishing the fins.

There's a great video from Apogee Rockets on the basics of papering, but I have a question:

How much do you need to sand before and after the papering? It sounds like just a quick "make it nice and even with 150grit" should be plenty for "before"... and after...Obviously, paper isn't thick, so you don't want to attack it with much of anything. So ...just smooth in the edges and then prime it? Hit it with some 300 or 600 to help the primer stick? Thoughts/help would be appreciated.

Also if you're papering TTW fins, do you extend the paper all the way to the fin root?

sand the wood smooth, paper (and let dry), seal the edges, then smooth the edges(if needed). if you sand untreated paper you will get the dreaded 'fuzies'. if you must sand, do so after sealing/primer so that you're sanding the sealer/primer. papering tabs, depends on what material I am using, balsa - yes, plywood - no.
plywood can be papered...but it can be more difficult to get a smooth fin because the glue will not soak in, so any excess glue left under the paper will create a bump.
Rex

I use Avery full sheet self stick labels.

Very easy to do. Just lightly sand the fins w/200 grit,wipe clean, and stick onto label. Trim and then treat edges w/CA and then final sand edges.

Works great for me.

I used fedex shipping labels the last time I papered fins - very aggressive adhesive.

Chris

I've done a tutorial on papering fins, and I've done it with plywood and balsa... in the same manner. Like Rex told you, don't sand the paper until after primer.

https://www.rocketryforum.com/showthread.php?65628-Papering-balsa-ply-Fins-A-foolproof-method

Oh, if it bubbles up during priming, don't panic, let it dry. It's my experience that it will lay down as the paint dries (don't watch it though, as that is almost as boring as watching... Well, you know... the grass grow).

I've only papered fins a few times, and just on balsa. I used a 'taco' technique that folded the leading edge over, vs papering each side separately.

Some advise I can give, is use as -very little- glue as possible. I also found burnishing it with something like a fat magic marker works well. I sandwiched and clamped mine between two sheets of heavy glass while drying. I used the glass from halogen light fixtures I had laying around...freebee!