Yep, I do it by a combination color of trics, and the red hairs as well. I am having a weird situation with my Purps right now, some of the plants appear to be like a week more mature than the others... lots of red hairs... some cloudy trics etc. The other bunch don't have any red hairs yet... so perhaps it will be a two step harvest though I'm not entirely sure where I will dry if not in the grow room and it's far too warm in there with the lights on to be hanging any amount of plant.

You can buy a 10X scope at a grow store or radio shack for pretty damn cheap... it gives you a great peek at your trichomes and should help you to know how far along you are.

BOL