It can be used, since they're independent clauses (you could use the phrases either side of the 'and' as standalone sentences). There is a special exception which means it potentially doesn't have to be used since the clauses are so closely-connected.
If it had been "use full sentences, and proper punctuation" then it would have been incorrect, since it has become a simple list. (But if you add another item, we have to get into the Oxford comma...)
It can be used, since they're independent clauses (you could use the phrases either side of the 'and' as standalone sentences). There is a special exception which means it potentially doesn't have to be used since the clauses are so closely-connected.
If it had been "use full sentences, and proper punctuation" then it would have been incorrect, since it has become a simple list. (But if you add another item, we have to get into the Oxford comma...)