Tomatoes are the number-one crop grown in most home gardens. They are the taste of summer and an easy vegetable to grow. There are only two things to remember about growing tomatoes: how to keep them healthy and how to keep them productive. Keeping them healthy can be as simple as choosing disease-resistant varieties, watering only in the mornings, and keeping all garden tools clean and sterile. Keeping them productive isn't hard to do, and sucker pruning is one way to ensure bountiful crops of big, fat tomatoes.
Identify the suckers. Wait until your tomato plant is 18 inches to 2 tall and is showing flowers. Look at the axils along the stem--the crotches that form between the main stem and the side branches. The small nodules or leaves in that crotch are suckers. Once you start finding suckers, they will get easier and easier to spot.
Pinch the suckers off at their base, where they meet the main stem of the plant. Apply hand sanitizer to your hands, then wipe them well on a clean towel. Use your thumb and finger and just pinch the base of the sucker until it gives. Use hand sanitizer before and after each tomato plant.
Use pruning tools, if you choose. Mix a bucket of water with 1 tablespoon of bleach per gallon. Dip your shears or scissors into the bucket before every cut. Cut each sucker at the base, as close to the axil as you can get.