Hi Venk
I haven't used Ply, but from experience from other projects, I think it would be a case of:
- sand surfaces
- brush and wipe down
- thin skin of filler to fill the grains
- rub down (oh, fun!!)
- give a coat of primer to show the imperfections
- rub down / fill
and keep going until you are happy with the finish
A random orbital sander is good for the big flat areas, and by hands on the curves.
I don't know any quick way......
But, if you do it now it will make for a White Christmas!!!!
Merry Christmas
Anthony