I use different tools depending on the occasion. I carry a single refill pencil which I use for simple note-taking and drafts and doodling. For more formal stuff, I use normal biros. For things that are important to me, I use good pens: a Parker ballpoint pen, or gel pens with a thick tip – these latter leave a nice and distinctive mark. Finally, I usually have real cheap biros with me which are for lending for other people and not minding if I don't get them back.

Also, I prefer whiteboards over blackboards because the chalk dust is bad, the whiteboard writing is more readable, and the whiteboard is easier to erase well too. With a few exceptions, I don't get to choose this one though, I just have to use whatever is in the room.