If I may add to that...

With some natural tinder it helps to get a knife and scrape it up, so you have either a fine powder or thin strands. Basically you want to get it finely divided so it gets hot before it conducts the heat of the spark away. A lump of wood, even most sawdust, is too big to heat up with a spark. If it doesn't get very hot it won't light.

I agree artificial tinder is best. On the other hand, you can only carry a finite amount so it becomes a bit like carrying a lighter with a finite amount of fuel, or a finite number of matches. A ferro rod is most important as a way to start an almost unlimited number of fires. So it's worth learning how to use "found" tinder - plants, or, in an urban environment, paper and cardboard - to get the most from it.