The best thing would be to study what Adobe and MS are doing with latest fonts, and read Adobe’s Feature File Syntax document which describes the syntax as used in FLS5 or FM.
I suggest that you also download Adobe’s example roman fonts (in the smaller box there is a link “ExampleRomanFonts.zip”) and have a close look at the files with “feature” in the name; these are very up-to-date models and cover almost all features currently supported in applications.
In the end, you have to tailor features so they match your fonts’ glyph sets and glyph names anyway.

OT How-to

Minion Pro
Bickham Script Pro

I think I would not recommend the old fonts as examples any more. Adobe has changed a few things, as described in Thomas Phinneys Facelift presentation. The sample font provided alongside the AFDKO represents current best practice.