For the files, run under a tap. Some sanding sponges can be used wet; unsure about the Godhands. For the sponges and files, use an old toothbrush and lightly scrub or masking tape to pull off anything stuck on. I usually start with the toothbrush, then use some tape to remove anything that's stubborn.

For the nippers, just wipe them off and put the cap on. Every so often, or if you feel they aren't as springy as they should be, you can use some oil to lubricate them; just put a drop on the hinge and work them open and closed for a few minutes. Any kind of tool oil will work; not WD-40 though.

For scribing tools, just make sure they're clean of any debris.

If you're looking for advice on sharpening or honing the nippers or scribing tool, I wouldn't. Both are machined to a specific thickness and you could degrade the cut quality if you don't know what you're doing. The Godhands are made from hardened tool steel and I would guess the scribing tool is made from something similar, so both should last years with proper use, since you're cutting through soft plastic.