One that has never failed me is Boy Scout Firestarter - white gas. But be sure not to use too much.

If you are in a situation where you can't gather good tinder or such tinder is soaked from rain, it is a good idea to have a stock laid by to get your fire ignited. As you can see, there are many different kinds. Next to BSF, I have always liked Utah Juniper bark. It is certainly worthwhile knowing about some that are not real obvious, like rubber and steel wool, just two of the many types with which I have no personal experience.