You did not mention how you cut it.
If you chopped it with a razor, you have to sand it round first. Then wet the sides of the tip with a few drops of spit on your finger. Burnish it by rubbing (turning) it in a piece of leather- it should get hot. Repeat.
In the lathe its the same thing- just easier. No need to sand, since the tip is flush after cutting. Wet and burnish it several times. Some people use water-thin cyano to get a really high gloss finish to the tip. I don't like to do that myself.
Once burnished, you can then shape the tip. DON'T shape it first, as you want the sides nice and hard before shaping to help it keep its shape. If you shape it first, you may get a bunch of mushrooming (even with a triangle).
The marker trick looks great but does not harden the sides of the tip. If you want it black, do this AFTER you have hardened it. A red sharpie can look trick too, as it will have a sort of dark Cordovan color..