First time trying bodywork-need advice....please
 

Hi,
I am hoping to learn how to do rust repair etc. It will be on my 2001 ML320. It runs great so I am hoping to keep it for several years to come. Since I use it in the winter, there are spots that have started rusting. I want to begin with the bottom of the doors. I need to know how to approach this repair. I have read through some books and watched several movies on youtube but would really like to get some advice on how to approach this.

Here are some pictures and thank you in advance.

More pictures

more....