Summarize this article:

As time passes, your hair will grow at the base of your scalp, creating loose hair at the base of your dreads. In other cases, your locks may have become loose or messy. If your dreads have any of these features, it's likely time to get a retwist.  You may need to retwist the base of all the dreadlocks you are working on, or you may only need to work on one side or section. While you work on a specific dread, use a rattail comb to outline the square perimeter of the lock. Then, clip away the surrounding hair. This helps prevent the dread from becoming fuzzy, uneven, or stuck to another lock. To retwist your dreads most effectively, you should use products while working the hair to freshen and strengthen it. At a minimum, you'll want some a rattail comb, clips, a towel, and dreadlock friendly gel or wax while retwisting.  Some dreadlock gel is specially formulated to help lock the hair of your dreads into ropes of hair. You might want to consider using this kind of product to help maintain your dreads. Some dreadlock wearers suffer from a dry scalp. If this is your situation, you may want to use a scalp cleansing serum before retwisting. If you're retwisting an entire head of dreadlocks, it can take quite some time before you complete your job. To ensure the best retwisting, choose a work environment that positions the dreadlocks at a level that is easy for you to work at. Depending on your height and body type, the ideal work height can vary. Generally, you'll want the head you are working on to be at roughly chest level. If you can, have the person you're working on sit in a straight-backed chair. This generally puts them at the right height and makes them easy to maneuver.

Summary:
Identify dreads in need of retwisting. Collect your supplies. Position the locks for comfort while working.