My old track frame, god rest its soul, had a perfectly sound paint job done by yours truly. Okay, it was black, which covers a multitude of sins, but it was pretty smooth and lasted several years; it was mostly okay even after languishing bent and twisted in the back of a shed for 20yrs.
Back to bare metal, Jenolite or similar on any rust, primer, rub down, primer, rub down, undercoat or top coat, rub down, top coat.
I just used ordinary car paint aerosols. Take care to reach the parts that careless sprayers miss (inside angles of lugs, under the top of the seat stays).
Hammerite used to be a swine to put on thickly (as recommended) without it running. They may have changed the recipe since.