Unless you are growing tomatoes which are a Bush variety you should remove the sideshoots from your tomato plants to focus your plant's energy into producing fruit rather than foilage.
A sideshoot is a shoot that grows at about 45 degrees from the main truss (stem) between the leaf and main stem. Take care not to confuse these sideshoots with the trusses which are the stems that produce the flowers, which turn into tomatoes. We find it is better to leave the top few leaves until we're sure they are sideshoots.
Simply pinch the sideshoot out with your thumb and finger.
Remove your sideshoots every week because the sooner they are removed the more energy your plant will out into fruit production.