Principles for growing long hair:

• It takes a long time. I've been growing mine for fourteen years, and it was at least seven before it was long enough to be at all remarkable. Growth rates vary, and mine isn't all that fast (4-5 inches a year), but it may be a long time. Don't get fed up and chop it all off.
• Stop doing damaging things. No more blow-drying or coloring or straightening or curling. Minimize the amount of product you put in. Never tease your hair.
• Get trims. A half inch trim every three months or so will take off the split ends and make your hair healthier.
• Conditioner is your friend. Use it liberally. As your hair gets longer, less of it will have any exposure to scalp oils. Be sure to condition all of your hair, not just the ends. I always brush my hair with the conditioner in it before I rinse. This makes sure the conditioner is evenly distributed and there are no tangles.
• Braid your hair before sleep to prevent tangles, and brush gently. Work knots out patiently, don't just tear through them.
• Don't wash your hair every day. Every other day is plenty for hygiene purposes, and more often is hard on your hair.
• Once your hair is too long to brush in a single stroke, pull it back in a bunch like a ponytail, and then pull it over your shoulder. Brush from the bottom up. *Bear in mind that not all people can grow their hair really long. Every hair follicle has a cycle, which is why your eyebrows don't grow down to your chin. The length a hair from a particular follicle can reach is the duration of the cycle times the rate of growth. These factors vary from person to person, and can also vary within a person's lifetime. If your hair gets to a certain length and the ends get really straggly even though you're taking good care of it, it may have reached its limit.

These principles should work for varied hair types, and should allow you to get your hair long. Hopefully, by the time it's really long, you'll be used to it and won't do anything stupid, like the time I did a backbend, adjusted my feet, and then tried to stand up without realizing I was standing on my hair.