Go to radio shack and get a 30x magnifying glass. Look at your trichomes. If there are no clear ones left you can harvest.
If you wait until 50% or more have turned amber your gonna get get a pain reliving high. If you harvest when they're all cloudy your gonna get a head high. Personally Id wait till 50%+ have turned amber. Dry and cure right and youll be smoking some fire.
Look into water curing. You wont get as much dry weight in the end but the smoke will be smooth and powerful.