This is the kind I have, they are a bit messy in the beginning because of the gel, but they look really beautiful. You can either just twist with gel or if your hair is long, you could start with double strand twists.
Advantages: It is all natural. You have control over the size of the dreads and how they form. Many salons are familiar with this method and the cost is usually much lower than a dread perm.
Disadvantages: It only works in African textured hair but that doesn't mean salons won't try it on Caucasian hair!
Hair should be sectioned into squares. Square sections make round dreads. Between 1" and 2" squares works well for most people. Smaller sections make thinner dreads.
As you section the hair you can secure each section with a rubberband. When the whole head is sectioned twist each section clockwise using a comb( using your fingers is easier than using the comb) to snag the hair at the ends and twist.
As each section is twisted dread wax/gel should be worked in to hold the twists. Thick waxes without petroleum hold the hair much better when starting the dreads. After the dreads mature thinner waxes can be used to add fragrance and sheen.
Hair should be twisted by hand regularly to help it lock up.
For the twists, I don't recommend using the rubberbands to hold them, or twisting too tight. You might be tempted to hold every single hair on your head but that only cuts/breaks your hair. A professional loctician can hold them easily without breaking, but please don't try it at home. If you twist too tight, the lock thins and falls off and we don't want that do we? Here is how to do it