The best thing you can do for yourself before you go is to study the Disney park maps.
You can easily get copies of each Disney park map by doing a simple Google search. You can download it or view it online. Getting to know the layout of the parks will save you time and make it easier to find where you want to go.
Once inside the parks, you can pick up a hard copy of the park maps and that will give you something in your hand to help. If you look at the maps ahead of time they will make more sense and you can even draw a path through the park.
Each park has a map and even a little bit of time giving them a once over or more will make far more sense once inside when you can put the real parks into your map mind. Getting around the parks is half the fun and while you can study them all you want, there is still something that will draw your attention like a popcorn stand or again, that big Mickey head pretzel.
Whatever you do, don't get caught up in anything but the moment of being there. It doesn't matter if you are flaunting one of the free pins that says First Time Visitor on it or wearing a shirt that says it in bold letters. Embrace your first time because there will only be one of those.