If you have been before and only have a day or so in the parks - think about what you and your family want to see and do and make a list.
Have everyone in the family pick something that they definitely want to check out and experience. Then plan around that.
If MGM and Animal Kingdom rides are on the list - try and do those early in the day.
Planning ahead even a little bit and help the stress level that day at the park while you are trying to complete your "mission" to see everything! Even taking advantage of Fast Pass at times or not using it can help you... also be sure to call in for a priority seating for a restaurant, even if it's that morning for that evening or lunch, you'll always be seated first with a priority seating than someone who just walks into the restaurant.
Also take note of park hours and if you are doing multiple parks in a day (which I have even done all 4 before in the middle of march) be sure to end at the park that closes the latest... decisions do have to be made on what fireworks display everyone would want to see the most, but if you have been before, maybe just hitting the rides is more important, or if you haven’t been in a while, try and pick a day when MK closes latest and check out the new WISHES; it's awesome!