The basic rules to intonation in English are rather straightforward:

With statements you use a falling intonation.

With questions you generally use a rising intonation.

With wh-questions you use a falling intonation.

NB! A question like "Would you like milk or cream?" when you've been offered coffee is tricky. With a rising intonation it is a yes/no question and they want to know if you want either or neither. If it ends with a falling intonation, then they are giving you a list to choose from.


With question tags you must decide whether an actual answer is required or if the question tag is more rhetorical, i.e. they are just hoping for confirmation.

If an answer is required, use a rising intonation.
If a simple confirmation is enough, use a falling intonation.