Super fun; I used to do this and make gifts for friends and family. If done well, on acid free paper, and kept out of bright sunlight, they can be relatively archival.

The linked article shows making cyanotype from outline if flowers, but far more fun IMO is digital negatives. There is a link to this at the bottom of the article, but I’ll share something I found that helps tremendously that wasn’t mentioned AFAICT.

When printing your digital negative, in addition to inverting your greyscale /B&W photo, you’ll want to adjust the curve, because the cyanotype will expose nonlinearly.

The best way to find the curve given your chemistry, photo, sunlight/latitude, etc. is empirically.

So, I recommend in photoshop/GIMP/whatever to generate a series of greyscale bars from #000000 to #FFFFFF, with perhaps a dozen or more steps. Put this alongside your image, then invert, and make a test print. You can then observe the nonlinear development of color and adjust the curve (remember, inverted) to apply to your final image for printing.

Probably I can think of more but this is already kind of lengthy on mobile :)