If you have a quest where you need to do something multiple times (like call places via the phone several times), don’t use up your energy. Instead, go and visit friends and use their phones. More often than not, you can (though some things like computer usage you might not be able to do this with). It will use up your friend bonus energy for the day, but it will also keep you from running out of your core energy – the stuff that only regains one point once every five minutes.