Hey! I'm a flint&steel man too. By F&S I mean the real piece o' rock and piece o' steel, not the magnesium sparkers. Not that I have anything against the magnesium things.
I'm always interested in ways to make your own charcloth from materials found in the woods. Do you use Foxtail in place of charcloth? Or do you put the charcloth in it?
Yes the sharpness of the flint makes a HUGE difference in the amount, and quality of the sparks. If you sharpen the flint and it still doesn't throw a good shower, try retreating the steel. Some folks heat it to a cherry red, and quench it in oil. Others wrap it in crushed charcoal, leather, and foil and stick it in the fire, remove after it is red hot and quench in water/oil.
Depending on what the type of steel you have to begin with will probably dictate what type of treatment method works best. File steel has carbon throughout the entire piece and will get brittle if water quenched. Milder steel may need carbon added and a colder quench.