Help fixing some rust spots

Hello. I have a '94 Acclaim and of course with it's age its starting to rust. I really don't feel like putting the time/money into cutting out the affected areas and replacing it with new metal. So i'm going to choose a less expensive option of using body filler. Does anybody have any tips / advice for going about doing this. If so I would greatly appreciate it.

Thanks.

Well I guess it depends where the rust is. The bottom of mine was rusted so I took fiberglass and a couple of metal bars and did it that way. The carpet hasn't gotten wet since. Bondo works pretty well I've used it before for other things. Shave it with a cheese grater while its still kind of wet so you get the excess off because sanding it takes forever. It might work for a quick fix so go for it. But if it's holes you're repairing it might take alot of bondo to fill in what a little fiberglass could do. Just kind of look at it from both angles. Good luck!