I don't have a suggestion for writing on it, and we generally toss instructions .. (I do have one of those thingies that goes on our desk that holds little papers and things go in there for a time ... then get tossed eventually).
But what I do if I really want to keep them is, cut them down to size, and tape them to my baking cupboard inside of the cabinet. I am the only person who goes in there and I have all my important info there. I have a ton of little clippings - it's high up, and I can find everything.
Some people (my sister) has a little cork board in her kitchen that only she uses, and she kept track of things there, and my husband has an inside of a cabinet over the fridge where he keeps numbers (like the guy who cleans our septic). It's just for really weird bits of info.
Eventually, when you've committed it to memory, you toss it so it doesn't get too cluttered. It works for me. I know it's there and can find it.