1. I highly suggest wrapping the roots (at least half an inch) with thread. This will help keep the dreadlock from growing bigger and bigger (this WILL happen if you dont keep up with them). I wont do single dreadlocks unless the person allows me to wrap the root.
2. Crochet every day. You only have a few, and if you find you can't keep up with your trial dreads, maybe you wont be able to keep up a whole head. Dreadlocks are probably the most highly maintained hairstyle (unless your doing the natural thang). It shouldn't take more than 10 minutes a day to tighten a few dreadlocks.
3. Avoid washing your dreadlock. Its alright to wash the rest of your hair with regular shampoo. If you plan on getting your whole head eventually, you should probably start cutting back on washing now. Skip as many days as you can until you can go over a week without washing. Because you will probably be using your regular shampoo, you will need to tighten them more than usual. They will loosen with each wash, and should be tightened up with a crochet hook.