Beside saving money, you save time by getting your park tickets in advance. Try using the search feature, type "discount tickets" and see the websites that are available. We used Ticketmania, but others recommend Undercovertourist. Tickets are discounted at the official Disney website, too. Just type in disney.com, or disneyworld.com. They all go to the official site, and you do save money getting tickets in advance.
You need to know if you are going to park hop at all so you can add that feature You need to know that the per-day price goes up minimally, so in the long run it is cheaper to buy a 10 day non-expiring pass that you may use in a future trip, as opposed to 10 one day passes.
We purchased 10 day non-expire passes, and they will be used for 3 separate trips.