Completely with you "Piltdown man",always try to avoid those situations check your weather briefing , however if you find yourself in such conditions I would say fly faster to ensure lift,avoid iddle setting on your engines to avoid flame out ,do anything you might consider to improve you chances to survival ,you are already in a very dangerous situation,know your aircraft and feel how is flying ,some airfoils are more sensible and tend to build up ice quicker than others,check your NNC,QRH.
Pray....
For unreliable Air speed at least in jets for a determinate Weight ,ALT there is a determinate THR setting and pitch angle for every stage CLB,DES or CRZ get familiar with them ,monitor always as if was your first flt, and if you see and/or hear unusual indications and warnings,crosscheck instruments check pitch att and THR setting and go to your QRH.
