On your tomato plants - I recommend picking off the laterals as they develop. 

If you imagine a tomato plant has a main trunk that grows straight up, with branches growing off this trunk at roughly 90 degrees. The laterals are the smaller stems that develop at approximately 45 degrees in between the main trunk and branch.

Often laterals won't produce fruit but can produce a lot of leaves. If you pick them off it allows the plant to put all its energy into growing fruit, rather than a whole lot of leaves you don't need. You can apply the same formula for working out the laterals on the main trunk, to working out which are the laterals your plants subsequent branches as well.