The near universal concensus seems to be an epoxy primer, because of its resistence to moisture and some claim a better ability to "bite" onto the raw metal.
After stripping the brackets, you need to thoroughly clean them using something like brake cleaner, lacquer thinner, or acetone, then a cleaner/degreaser such as PPG's DX330. All chemical traces of both the stripper and cleaner need to be removed in order for the paint to adhere properly. Once the bare metal is in its "raw" state, then wipe it down with metal prep or conditioner, which is a phospheric acid-based product that etches the metal so that it is ready to receive and hold onto the paint. After that, lay down the epoxy primer in 2 or 3 light coats, with the appropriate flash off time between coats. PPG makes a very good product which they call DPLF (the EPA-compliant successor to DP). There are different numbers following the DPLF label, and these numbers indicate the color of the primer: red, green, white, grey or black.
If there is rust on the metal, before beginning the cleaning process wire wheel the rust to get off any loosely adhering rust, then either neutralize it or incapsulate it. Products sold by Permatex will neutralize. POR15 will encapsulate. SEM's RustMort is also a neutralizer.
If you are only painting these pieces, using a spray gun may be too big of a deal, it is the best method however.
If you wanted to use rattle cans, clean and prep properly and use some Rustoleum non-sandable primer and topcoat with your choice of color, which should match the rest of the clip.