I usually use matches for speed, but I also have a few steels and one Tudor-style steel that requires an actual flint. You can catch a spark with cotton wool, especially if it's got a bit of petroleum jelly on it, but that's not the greenest option. Scraped wood or dried grass makes good tinder but since a season volunteering as a re-enactor at a Tudor farmhouse near Straford-upon-Avon, I've always meant to make my own charcloth.
Charcloth is to fabric what charcoal is to wood- you take fabric made from natural fibres and then heat it in a controlled way so that moisture is removed without allowing the fabric to burn (pyrolysis). The resulting charcloth takes a spark very easily so is perfect for lighting fires, with a steel or matches. It's also slow burning, so no panic to drop the burning cloth, and easy to keep dry.
I have a stash of old cotton tea towels that look rather grim, so I pulled the synthetic label off, folded it into four lengthways and loosely rolled it so it fitted perfectly inside a golden syrup tin. Any tin would do- if you only want to make a small amount you could use a furniture or shoe polish tin or even a travel sweet or mint tin, cutting the fabric to fit.
Put the lid on and then, as you want the gasses to escape, pierce a hole in the top with a nail or bradawl.
You can heat it over anything but in a fire is most fun so while cooking I put the tin in a hot area of the fire with lots of embers and pretty quickly saw gas coming out of the hole.
I turned the tin a few times to make sure it was evenly heated and then when the gas had tailed off, removed it from the fire and stuck a twig in the hole to prevent oxygen getting in and igniting the charcloth whilst it was still hot. (If oxygen gets in whilst it's still hot it will catch fire and burn.)