I have two children. The older one is 3. Depending on the situation there are usually many possibilities. For example, last week she was unwilling to share the swing with other children and had a temper tamprum. After a single warning we left the playground with her, ignoring her loud protest.
If she makes trouble in the evening the threat not to read her a bedtime story usually suffices. We had to follow through on it just twice.
It's not that hard. Children have toys and priviliges they care about it. Parents usually know exactly what these are.