I have a small patch of rust on my drivers side door sill.  Doubt it would qualify for the VW warranty a it looks like it has been touched up by previous owner and is now beginning to bubble through.  Has anyone else tried a bit of DIY on this area?  I am not looking for a perfect job given its location and the fact I will be probably moving the car on as a trade in in the next 1-2years, just looking to stop the rust advancing so don't think its worth body shop prices if I can DIY.
Any recommendations on products?  Guess its a case of wet/dry sand down the rust, apply some rust eater / primer, spray paint small area and then clear lacquer?  Any advice would be appreciated.  Thanks!