Ford Fiesta rust issue

Corrosion on a-pillar and boot panel of Ford Fiesta

Hi Scotty, I have an '01 Ford Fiesta and it has developed rust issues in two places, specifically the lower a-pillar and the boot panel. It's only surface corrosion at the moment, so naturally i'd like to sort it before it becomes a bigger problem but i'm not sure how to go about fixing the surface rust. Can you give me any advice? Are rust preventatives worth using? Thanks

sand it down, then paint it with rust preventing primer made just for that. Many companies make great anti rust primers for cars