It also helps to oil them if you won't be using them for a few days or weeks.

Automobile oil, used auto oil, and mineral oil are all good.

Maybe keep a bucket with some coarse sand or gravel and some oil, them mix it up and plunge to shovel blade a few times to clean and oil it. But it's easier to spray the shovel with water, let dry, and rub with oily rag.

I put mineral oil and/or beeswax and/or parafin in wooden handles, because they get a lot of rain on them.

You can even rub some Johnson's Wax on a steel tool before winter storage. The wax dries to a hard film. But oil works about as well and is easier.

Where's my sharpening stone
I used to have it nearby. Several household moves later and it's forgotten. Must be around here somewhere

Yeah! YEAH!

A file works too, even an angle grinder, but not as well
I used to have two hardened steel sharpening guides, one of them a great Buck HoneMaster, lost long ago in a move, in a box that neve5r made it to the new place. (GRR!)

Now I make do with flimsy, shaky plastic cheap things.
Oh, well, that made me learn to hold knives more steadily by hand.

DMT Knife Sharpening Guide
https://www.amazon.com/dp/B00004WFUR/

https://www.amazon.com/dp/B000FKM41S/

With a magnetic dingus added, and a video:
https://www.amazon.com/dp/B001E7BMW8/