The most important part of this endeavor is to purchase healthy plants that are suited to growing in pots. There are several varieties around that are well-suited. Some are called "patio tomatoes". Most sizes of tomato (from cherry to the largest) have at least one variety suitable for growing in a pot.
Step2
Make sure your pot is big enough, and use good quality potting soil! This is important. Follow instructions received with the plant for best growing. Keep in a sunny area, away from animals (My cats LOVE chewing tomato plants!)
Step3
Make sure to select an area of your house without drafts. Too cold in the winter and your tomato won't continue to grow. Also be wary of air conditioning/heat vents around your potted tomato.
Step4
During the winter months, supplement the light from outdoors with a grow light bulb, available at most hardware stores. Use a clamp lamp to clamp above the tomato plant for best results.
Tips & Warnings
Be careful to follow watering instructions for your plant! Too much, and the roots will rot, too little and your tomatoes will dry up!