I've read many threads about skin types, irratation, etc. Is there a reference as to how you diagnose your skin type? My skin gets irratated and slightly red around the neck area (several inches to the left and the right of my adams apple). My skin will get dry as well. Isn't neck irratation pretty common?

Now my follow up is this. Is my skin irratated due to shaving factors or due to my skin type? Same question goes for the dryness? I currently use a Mach4 razor.

When purchasing shaving soaps, should I go for soaps that focus on dryness & irratation or would normal skin type soaps be fine?