There are basically three types of tomatoes and various ways to treat them. So I will explain how to treat each type .
Cordon or Indeterminate Tomato Variety
Your standard upright growing plant. Remove all side shoots once a week, unless you damage the head or have pinched it out by mistake, in this case leave one shoot to take over the head.
Leaves. Remove the tiny seedling leaves after the plant is about six inches high. The rest of the leaves should be left on as long as possible, as a rule of thumb, remove the leaves as the plant grows below the ripening truss, or if you see a damaged or weak leaf. Other leaves can be removed to give a good air circualtion, but only a few between each truss. If the fruit is exposed to too much sun, they will ripen too early.
If you are using the arch system and growing you plants over the top of the path, then only remove the leaves that are hanging down to give you head room.
Stopping the plant. Tomatoes can grow to about 20 feet in length or longer, if looked after correctly, but I do not think many gardeners will grow them that length. The best time to stop them is a month before the end of the season, or if you feel they are looking past their best. Stopping the head will let the plant concentrate on the fruit set on the plant, and they all should mature and ripen correctly. Outdoor tomatoes, are usually grown to the top of the support cane, so obviously stop these earlier.
Bush or Determinate Tomato Varieties
Bush tomatoes differ in that they do not need side shoots removing and are effectively self stopping. Remove only lower leaves if they get damages by laying on the soil.
The drawback of this is that they take up more ground room, so are better grown outdoors if you need to get a good crop form your valuable coverered space in the greenhouse. They do not generally require much or any support but the fruits are often in contact with the ground, which means more vulnerable to slugs and other pests. So it is a good idea to give them a little support with a frame. They can, in poor years, leave you with more green and under-developed fruits but you can compensate for this if you can get them off to an early start.
Dwarf Bush or ‘Hanging Basket’ Tomatoes
Unlike the standard determinate varieties of tomato, these are smaller plants usually giving cherry tomatoes and are bred to grow in containers such as hanging baskets. and again, you not need to remove side shoots or leaves.