How to Tie Tzitzit
1. Before you try tying tzitzit to your tallit, it is advisable to practice with twine or heavy string looped around a chair leg.
2. Although you can spin or devise your own tzitzit strands, it is easier to buy a tzitzit pack, which is available at most Hebrew bookstores.
3. There will be 16 strands in the pack–4 long ones and 12 short ones. Separate these into four groups with one long and three short in each.
4. The longer strand is called the shamash [or helper] and is the one used for the winding.
5. Even up the four strands at one end and push the group through one of the corner holes in the tallit.
6. Even up seven of the eight strands (the four being doubled) and leave the extra length of the shamash hanging to one side.
7. With four strands in one hand and the other four in the other hand, make a double knot near the edge of the material. Take the shamash and wind it around the other seven strands in a spiral–seven turns. Be sure you end the winding where you began–otherwise you may end up with 7 1/2 or 6 1/2 winds. Make another double knot at this point (four over four).
8. Spiral the shamash eight times around. Double knot. Spiral the shamash 11 times around. Double knot. Spiral the shamash 13 times around. Final double knot.
This is the common, and halakhically [according to Jewish law] precise type of tying. There are, however, two variations on this:
1. A Sephardic tying adds another dimension to the pattern: each time the shamash is brought around, take it under the previous wind before winding it further. This will produce a curving ridge around the tzitzit. This, too, should be practiced before trying it on the tallit.
2. Although not in strict accordance with the halakhah, some tie the tzitzit with the shamash spiraling 10-5-6-5 times respectively.
Sources: Essential Judaism, myjewishlearning.com