First of all, an onglette is not the graver you want to use to sign your name.
It will cut a very thin straight line, and give no definition to your cuts.
The simplest, especially for the least experienced, a 51 or 52 round graver. If you have some experience, either a 120g square, or maybe any other square graver.
As far as sharpening, sharpen the face, then relieve the heel about 15deg,
Hope that helps.