What would you advise your son about dating?

I would advise him to be attached to God, not people or other things. In that case, he won't be overwhelmed with heartbreak and all that stuff

And, of course, being upset is being only human, but the suffering can be reduced.

And this idea isn't unique to Christianity, but is also in Buddhism.
 
Being controlling is what women hate. You have to learn to let go when not welcome and that also helps chances of her coming back.
 
The only thing I would mention to my son is the fact that before getting into any kind of relationship, it is important for one to respect personal values and worth. I would also make sure that I make him respects others, treats them gently as he wishes to be treated too.