White or brown?

Brown hairs are dead. Calling them orangish or reddish helps to separate references to necrotic stigmas from references to ripening ones.

There is no rule of thumb about the percentage of red hairs that governs all plants. Some plants are better with more of them while other strains are better with fewer. The only time that you can really use this as a good way to judge when to harvest is when you know how that particular strain looks at harvest time. Most pot plants will be ready to harvest somewhere close to 50/50-40/60 white/red. Sativas will generally be better with more red hairs and Indicas with a heavier high will generally be better with fewer. For example, my least sleepy, most sativa strain gets chopped around 25/75. The heaviest, sleepiest indica I ever grew needed harvesting at roughly the opposite of that ratio, around 70/30.

Imho, clipping a bud from the middle of the plant, quick-drying it and then smoking it is the best way to determine the ripeness of an unknown variety. That way you know exactly how the high is progressing.

 

dont determine readiness of buds by the color of the hairs. use a scope or strong enough magnifier to examine trichomes.

 

Wait until they are cloudy, with a very bulbous tip. Should be looking like golf balls sitting on a T; can't see thru them, nice and fat.

 

Depends on the high you want; you also wait for amber heads. The heavier high you want, the more ambers you want. There are other signs for harvest too; feel of the bud (tight and dense) and smell.