Here's some interesting tips about visiting Disneyland, including my personal favorite:
As with all amusement parks, try to sneak in your own drinks, especially in the summer. There's a Food For Less store about a mile up, at Katella and Euclid. Drinks inside the park will normally cost about 2 dollars. Your bags may be searched when you enter the park so conceal your drinks in the bottom of your backpack and cover them with Kotex or Tampax pads. This should discourage park attendants from searching down too deeply, especially if you're a man.