I tend to use them in everyday writing, but try to avoid them at work as our house style guide tells us not to use them unless the meaning would be unclear otherwise.
Only use a comma before ‘and’ in a list if the meaning would be unclear without it. For example: ‘The learners studied catering, key skills, and information and communication technology’ (where ‘information and communication technology’ is one item in the list).
Build a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life.