Buy your tickets in advance. You can almost always get a discount, and at the very least you can skip one of the many lines by buying and printing your tix at home. Check MouseSavers and Theme Park Insider for the current deals. If your trip is totally spontaneous, whip out your membership cards–AAA, AARP, whatever–at the ticket booth to see if you can win a discount.

Bring snacks. Theme parks vary on their policies about outside food, but most will you bring in a reasonable number of drinks and snacks, as long as you’re not hauling a cooler. Speaking of which:

Consider stashing a cooler in your car. Fill it with lunch fixings, and repair to your car rather than an overpriced restaurant at lunch and dinner times.

Buy your souvenirs elsewhere. If there’s a Wal-Mart near the park, chances are it will carry related merchandise. You can also find discount Disney souvenir stores near both the Anaheim and Orlando parks. If you must buy souvenirs, shirts and caps at the park, do so at the end of your trip, when you’ve had a chance to view all the available options.

Give your kids their own money to spend. Otherwise, you’ll be nagged all day long for treats and souvenirs. Give them $10 or $20 with the understanding that when that money is gone, it’s gone.

For more, read:

The penny-pincher’s guide to theme parks