Plant deep.
Bury a tomato plant's stem and the stem will sprout a slew of new roots that help the plant grow sturdy and tall quickly. You can bury just about all of stem--pluck off the branches below the top flush of leaves.
Early in the season, when the soil is still cool, dig a trench 4 or 5 inches deep in the soil and set the transplant into it, again burying the stem up to the top leaves.
If you're transplanting later in the season, when the soil has warmed or in dry climates, bury the transplant in a straight, deep hole. Cooler, moister soil below 6 inches deep helps tomatoes survive in hot, dry summers.