So what if people laugh at my excel spreadsheets, 15 page Word document of tips, and tub of "for the next Disney trip" items. When friends are planning a trips, the inevitably come to us planners for advice AND we have the best vacations!
As for other tips - If you have kids, even up to 8 or so, don't underestimate the value of a stroller. Tired legs make for loud whiners and less fun, especially if you plan "commando" days. They can also double as a place to store souveniers if you can't send them back to your room. Also for my kids, I got double sided velcro and wrote my name on and cell phone number on one side then folded it in half through their shoelaces.
For autographs, I cut a bunch of 6x6 squares (including one heavy cardboard one) and threw them in a manilla envelope with a sharpie. When we met a character, we gave them one sheet and the sharpie to sign with. When we got home, I used the unused squares as matts for photographs and using some stickers and 6x6 toploading albums put the photograph on one side and the signature on the other. The kids had great and EASY albums to show friends their trip in less than an hour.
Take a small chamois cloth - you can find it in the automotive section - to dry off wet seats, bleachers or yourself. They are small, hold amazing amounts of water and can be wrung out to dry in short order.
Wear good shoes and have a decent back-up pair for when the first pair gets wet from rain or ride.
Last, if you aren't REALLY used to walking alot, walk a few miles a few times a week in the month before you go. You will be able to do and enjoy doing so much more if you can keep up your pace. You'll NEVER see it all in one trip, but most of us like to try!