Don't wash with salt water.

If you take care of everything else (diet, exercise, medication) then simple good hygiene should give your penis all the protection it needs.

You may not be too keen on pulling the foreskin back, but that is essential (not necessarily when peeing, but for cleaning.)

Once a day at the very minimum, you should pull back the skin and wash thoroughly but gently with a mild soap, and rinse thoroughly. It doesn't matter if you dry it or not.

If you want to be extra careful, use a small amount of bleach in the laundry when washing your towels and underwear. That will kill any residual fungi that could be re-transferred.

Keep it clean and try not to do anything that could cause abrasions (over-using it, masturbating without lube, scrubbing too hard in the shower, etc.)