I know this is a fairly common problem for the S13, and my car is no exception. Its still pretty minor, but I would like to fix the problem before it gets any worse. Has anyone had it fixed before? If so, how much?
Touch up paint 
All I had was a little bubbling…so I rubbed it off with this fibreglass pen thingy then put some touch up paint over it.
Take the struts out and pressure wash inside the towers. Scrape off any rust with wire brush, and use something like PO15 to cover up the rust them undercoat on top of it. Its rusts from under the strut tower so make sure you undercoat everything.