Black Metal Paint Touch Up

Can anyone give me advise on how to touch up the little rust spots on the steps and frame? I want to keep these parts looking good as well as stay ahead of the rust. I am hoping to be able to do it myself while on the road and inexpensively.

Sand the spot down to bare metal and spray paint it. I kept a 5th wheel hitch looking like new for about 13 years this way.

I scuffed my steps with a Scotchbrite when my trailer was new. The steps were all faded from sitting on a lot. I masked all around them and primed with Rustoleum. After that dried I painted the with Rustoleum spray paint. Put on a couple coats. They still look good. I suggest buying the most expensive spray paint in a can you can find...Paint everything not just a spot here and there. You will get what you pay for...Don

I appreciate your replies. Pretty much what I thought but felt it worth inquiring as I have a lot invested and want to take care of it.

I have spot sprayed small rust spots with Rustoleum without getting crazy with prepping or stripping.
When I received my rig, it was pulled over salted roads in winter and the dealer failed to wash it right away. After just spraying the areas with black Rustoleum they still look good almost 3 years later. Trace

When I was a young (read low ranking) soldier we had a thing called Motor Stables and one of the primary tasks was "spot painting" where any rusty spots on the vehicles were cleaned and painted. To this day I do the same thing on my rig only I use the Rustoleum glossy black paint in a pint can and a small brush because the spots are usually small and don't warrant all the masking that one does for spray painting.