Some personal definitions of turbulence :
Light : A half full cup of coffee starts to spill over the lip.
Moderate : All the coffee spills.
Severe : Were's that cup gone ?
On a more serious note. There are often subtle clues to the onset of "some" turbulence, other than the obvious nasty coloured bits on the radar.
If you are under a Cirrus layer and that layer has curling threads coming down or up from it. There's a fair chance of CAT around.
An early indication of mountain / standing wave is often found by watching the N1/EPR changing. The rougher "cobblestones" are on the back (downwind) of the lift, so you get more warning running downwind than into it. (ie you get the lift = EPR down, then the rattle.) Remembering always that the strongest waves are often "Blue" (clear air). The lenticular are on the top and are a good indication if you can see them. Just downwind of the lenticular is (theoretically) the worst place.
The best thing you can do when you get a "cobblestone" rattle going upwind, is get the speed back to Turb PDQ. Flying into wind a good "rattle" is nearly always followed by a lift surge. The boundary is often sharp and you can get a disturbing increase in IAS as you cross into it. But don't be too sharp on the throttles - what goes up, must come down. You just get the power all the way back and you hit the sink. Equally nasty and potentially terrifying. Nothing spools up slower than a big fan at F350.
An idea, since that is all I can offer. Consider the use of speedbrakes in the lift/IAS surge to control an increasing speed. Leaving the engines spooled up for the sink that is sure to follow. Mercifully we meet high altitude wave infrequently, but the fact that it is waving at high altitude means it is rarely benign
At turbo prob altitudes you can usually bet on a lee wave front being formed if the wind is within 30 degrees of normal to a mountain range. However with the amount of lateral shear that goes on above that it is often a difficult one to forecast. Also no-one supplies TeFi Grams any more, so spotting any associated stability layer is impossible. I personally just watch out for wave <300 nm downwind of any significant ranges. If you can "sniff it out" early and get the seat belts on before you hit it, you win. Sometimes you get it wrong - but it is on the safe side.
Any change in OAT means possible CAT about. The rule I follow, that seems to work is "follow the temperature". OAT UP = climb for smoother air. However I suspect this might be like coin flipping at times. Any better ideas on this "method" would be much appreciated.
Now this is a strange one that I have only just started noticing. Perhaps because we are at last getting most of the "fag smoke" out of the filters. After an hour or so of clear air cruise, the filters are obviously very dry. When you get into a layer of higher humidity - not even cloud - then you get a faint smell of what I can best describe as "warm bakalite / circuit boards". This always seems to preceed a bump.
And as for the speed. Get back to Recommended Turb Speed early. It gives you a better set of margins, a slightly softer ride and does no harm.
Some links on Wave that you might find interesting. Mostly culled from Gliding links.
Nasa Met - Mountain Wave
DG Gliders Wave Page - Good Diagrams
MUST READ ON Mountain Wave associate CAT