Count the number of plants for which you will provide wicking. Then head off to a craft shop or anywhere that sells string, yarn or thin rope. The circumference of string you'll need will vary depending on the size of the plant and the container. Use more slender strands for smaller plants, and wider wick material for larger ones. You'll also need a container with a lid -- butter or margarine containers work well, as do those for many dairy products.
You have two options for placing wicks. One is to add it to the plant soil when actually potting the plants. This is the simplest method, as you simply run a string down down through the soil from the top, out a lower drainage hole, and leave it extending the appropriate number of inches at the bottom. The other method is to poke the wick up from the base of the plant. To get the wick deeply enough into the plant, some people use long needlework needles to string it through the soil.
Poke or cut a small hole into the lid of each container you'll use. Run the lower part of the wick through the lid. Fill the container with water and replace the lid. If you need to remove any slack in the wick, just tug it gently through the lid -- it's OK if extra wick remains in the watering container. Just be careful not to pull the wick out of the plant. Allow the wick to work for a couple of hours, even overnight, then check the soil to see if it's moist. Your plants should be just fine with this system, and the soil remains moist.
When preparing for a trip, and after you are assured your plants are indeed self-watering, all you need to do is fill the water containers to full capacity before departure. Now, if you plan to be gone for a month, you probably need very large containers, or to ask someone to refill the containers while you're gone. Also, even if you remain home, it's easy to forget about plants if you aren't routinely watering them, so determine a system that works for you so your plants remain thriving.