Here is what I found.
1) Plastic wood works well. You have to mix it up well... and take a small amount out to use. It tries quickly so you want to keep the container closed, get small amounts and use it quick. After a minute out of the can, it is too dry to use.
2) Try not to use to much... especially on the edges. Why? You probably don't want to sand that much. And breaking it off after its fully dries can break more off then you want.
3) After about 10 minutes... you can do a little last minute shaving and molding. I don't know if the long term effects are going to better/worse because I touched it after a few minutes before it was completely dry. But it really helped when sculpting areas.
3.5) After about 15 minutes I could do a quick sanding that moved a lot of stuff easily. This was good any place I put too much.
4) Only spread in ONE direction with a putty knife. Putting it on in one direction, then another made it peal up a little and create cracks. It never seemed to work as well as doing it from one direction.
5) When doing an edge.. put just a little more then you need on the putty knife. press down on the edge so that the putty just pushs over the edge and then move the putty knife back away from the edge. Did this make sense?
6) When filling in a big big missing area (bottom corner) I removed all the extra crap... then I filled it in with a few coats of putty. Molding it like I mentioned before. It seems strong... but I haven't really tested it.
7) Removing tmolding before is MUCH easier... but not necessary...
Anything else?