JC - as A37575 stated, decrease sensitivity at low altitude, increase sensitivity(gain) at high altitude. Newer aircraft can reduce gain below the old 'auto/calibrated/normal' setting.
Tilt is inverse to altitude. Low alt = tilt up, high alt = tilt down.
Rapid increase in intensity is not good.
Practice(gain/tilt) with storms you can see as you manuever past them. Use that knowledge(experience) at night or when you're in clouds (IMC) and can't see the storms.
Not a fan of the official guidance in the AFM's re: radar use. Air France President spoke about another flight (AF?) hitting turbulence at altitude along the same route as AF447. Said the Captain switched to a more sensitive setting (that is not AFM guidance..) and changed his route of flight based on the new radar depiction.
After all this there is no guarantee about weather you're penetrating. Sometimes it's better, and sometime it's worse, than you'd expect.