When you are planting tomatoes, you want to plant them deep. Tomatoes have a fairly unique property in that any portion of the plant stem that is underground will send out roots. So, when you are planting your tomatoes, remove the first set of leaves, and put the plant deep into the ground.

You should try to get at least half of the tomato plant into the ground. Yes, this will make your plant look tiny when it is first planted, but the extra roots that this provides will result in a healthy plant later in the year; one that produces much better tomatoes.