I'd hit it with a wire-wheel (scouring pads are fine too, they just take longer) and then spray or brush some Rustoleum Hammered on the frame. I painted mine a year ago and in most places it's doing pretty well. I painted one of my rusted-to-hell DT3Ks at the same time (with absolutely no prep-work at all) just to see what would happen. Can you tell which one?
2001 TJ Sport 2" coil lift, 31" TrXus, swapped in 3.73s, ORFab cage, Aussie front locker, A to Z Fab rocker skids, JeepMedic Oil Pan Skid, JeepMedic LCA skids, Alloy USA D30 Seals, Warn Diff Skids, Cobra 75wx CB, Jeeperman prototype front bumper, 9.5ti, custom rear bumper, Rokmen frame tie-in kit.