Stopping rust - short term
I've had my car since April, and since its arrival, it's started to sprout surface rust in a number of places, just a few spots at first and over the last week, more and more. I've had the doors apart, and there's only a little very minor surface rust on the inside, the floors and most of the trunk are fine, and up under the front nose is basically OK, won't hurt to put some POR20 on it or something. Despite the relatively rust free areas I can check, I'm scared by the spots that are popping up all over. (I'm probably making it sound worse than it is, but I'd like it to stay that way...)
I'm going to look at having the car painted in the fall after the rain stops, and bearing that in mind, is there anything I should do right here, right now, that will a) stop the rust, and b) not complicate my pending paint job? Doesn't have to be pretty meanwhile, I just don't want to do anything that'll double the prep time I'm paying for when I have it resprayed if I don't have to, and I don't want to assume what works and what doesn't.
Thank you for your help.