Paint prep

[72YloSB]

I am beginning to prep my car for paint, and so far I have been successful with simple hand sanding(I plan on going down to bare metal.) What grit paper should I start with, and work my way up to? Is hand sanding ok, or is this a bad idea? As soon as I get the sanding done, I plan on using Bondo to fill the holes and imperfections, and need to find a primer that I can drive with for now until I can afford a good paint job. Does this sound like an ok plan? Any suggestions are welcomed and appreciated.