Try not to take it 2 days in a row. If you do, it should be infrequently. At the very least you should be taking a couple days a week off. As a rule of thumb I try to take one day off for every day of use, three days off every other week, and one week off every other month.
Don't binge on it. Manage your time accordingly so that you aren't staying up 24+ hours. Sleep is incredibly important and nothing will build amphetamine tolerance faster than binging. Generally if I can't fall asleep I will take a vitamin C capsule (lowering the pH of your stomach will remove amphetamines from your system much faster) and some melatonin. If I still can't sleep I'll take an ambien although I realise not everyone has access to it.
Chelated magnesium. I swear by the stuff. I take it twice a day and not only does it noticeably increase the drug's effects (I've heard some people claim that taking it while on amphetamines reduces the effects, however in my experience it completely strengthens them) but it also severely reduces the rate at which you develop tolerance. There also are other forms of magnesium that work such as magnesium citrate. Just avoid magnesium oxide as it has almost no bioavailability whatsoever. (iirc 4-8%)
As a bonus I find that it helps to track which days I'm taking my medication. I have an excel sheet I use to track every substance I put into my body from mushrooms to caffeine. I also have one specifically to track my Vyvanse prescription that offers some additional data. As a result I can tell you how much and how often I have taken it since the day I started. Doing this has helped immensely in determining whether or not I have been using it too much.
I've been taking 60mg of Vyvanse for about 6 months now and have experienced no increase in tolerance whatsoever. I experience the same focus and euphoria from it that I did on day one. I'm actually taking the month of February off as well after coming to terms with a few things during a fairly intense trip I had yesterday, however by no means do I think I have a problem with it. Amphetamine addiction is very real though and should not be underestimated. Be careful with the stuff and you should have no problem with tolerance or dependency.