During rounds a bit of soap and water on a golf towels, clean clubs and groves between shots, then thorough cleaning after the round. If you take care of your clubs, they will pay it forward! Clubs are an investment, treat them like it......

After every round, spray faces with Fantastik, nylon brush to clean, another spray to clear the dirt. Wipe clean to dry. Been doing that for a decade. Never an issue and they look great.

Here is what I do:

On-course: Wet towel, Grooveit Mini - quick and easy - clean after every shot
After each round: Clean grooves, shaft, grip with water and toothbrush for the grooves
Every few weeks I clean my grips with mild soap and water - I like the tackiness

As annoying as they are, head covers for your irons keep them pristine and have been a life saver to keeping my T150/200's mark free (for the most part)

Hope this helps!