Disneyland and Walt Disney World experience huge upswings in visitors during certain times of the year. These peak times include the summer months (June, July and August), the weeks surrounding Christmas, and the spring break period of mid-March through April.
If you go to the parks during these periods, expect long lines and heavy crowds. If you can go during "off periods" -- January, February, early May, and September through Thanksgiving -- crowds will be much smaller. You might also consider going during a weekday instead of a weekend. The parks tend to close earlier, but you will more than make up the time with shorter lines.
Disneyland resort contains two separate parks: Disneyland itself and Disney's California Adventure. Disney World contains four parks: Magic Kingdom, Epcot, Disney's Hollywood Studios and Disney's Animal Kingdom. You can easily spend an entire day exploring each one. While Disney offers park-hopper passes for an additional fee, allowing you to jump between parks on a single given day, it usually makes more sense to avoid that extra cost and just plan to visit one park each day. This is especially true at Disney World, where jumping from park to park can involve up to two hours of driving, parking and waiting in line at the entrance.
Disneyland is a little easier -- the parks are less than 500 yards apart -- but the principle remains the same. Look for "two-fer" deals, which give you tickets to two parks on different days for one price, or Disney World's standard "Magic Your Way" tickets, which let you visit one separate park per day. Both will save you money and prevent the heartache associated with trying to squeeze multiple parks into one day.
The sheer glut of things to do at Disney resorts may entice you to fit as much as you can into a given day. This can prove to be a mistake, especially if you have more than one day to enjoy the resort. Look for a few hours in the middle of the afternoon to head back to your hotel and take a nap. Alternately, just look for a quiet place in the park -- all six have plenty of relatively empty corners where you can sit, catch your breath, and recharge your batteries.
If you're there for multiple days, plan to spend one just relaxing by the hotel pool or playing games in your room. This is especially important if you have evening activities or you're traveling with small children. You'll feel more rested and have additional energy for the rest of your visit.
Food in the Disney parks can be expensive. Luckily, you can bring your own into the parks, saving you money and helping you stretch your vacation dollar. Disney forbids hard-sided coolers and glass bottles, but soft lunch bags are permitted. If you do want to eat in the park, look for meals that you can divide: portions are often large and splitting a meal can save you a great deal.
You are not obligated to stay in a Disney hotel to enjoy the parks. The surrounding streets of Anaheim are full of hotels at which you can stay at a considerable discount; most of them are within walking distance of the park, which saves you money on parking, too.
Orlando hotels are a short driving distance from Disney World, but many of them offer complimentary shuttle service to the parks, which saves a lot of money. If you have an RV or camping tent, you might also think about staying at Disney's Fort Wilderness Resort, which lets you "rough it," while still providing easy access to the Disney World attractions.
