I think the most important thing you can do, if creating a handwriting font, is simply to create multiple versions and come up with a way to pick glyphs from them at random when composing text with it. If you don't do that, your font will never, ever make it out of the uncanny valley, no matter how much work you put into getting the details right.

I get so much junk mail that tries to fool me into thinking it's addressed to me personally with script-style fonts. Some of the fonts are very nicely done, but all I have to do to dispel the illusion is to compare two instances of the same glyph and observe that they are identical.