Rust removal best practices

I have a bit of minor surface rust and built up dirt on the inside of my 68 mustang as well as very light rust on the outside, and have stripped the interior down to metal. What are some best practices when stripping the paint/rust from the car, what tools/chemicals do y'all recommend? This will be my first time doing this. I'm doing this in preparation for having a new left floor pan welded in.

Thanks  

Stripping can be done many ways, liquids, gels, abrasive media, or sanding.  For most home jobs sanding disks (air or electric) are about the easiest.  You have got to be careful about heating or deep scratching the metal too much if you sand.  After that there is a clear metal prep solution sold at most paint materials places that you should wipe down the metal with after stripping it.  This will help protect the metal against quick rusting that does occur.  If not getting to the rest of the work for a while use a thin layer of primer that can be taken off to complete the work.