We like to stay at a new resort each time (at least we try it depends on the deals/ prices for those dates) so something I like to do when we are really far out in advance (before you can even book) is think of where we might want to stay and read many reviews, watch lots of
youtube videos and have my top picks. I feel less biased when I don't know what the pricing will be between the other hotels in the same category.
I start to stalk flights as soon as they become available.
If you're planning on doing dinning reservations... you can take your time going through every menu, reading reviews and deciding where you're going to want to eat!
I also go on Disneystore.com or on the Shop parks app to see if there is any new merchandise available. I don't ever buy anything unless there is a sale and will use it for the trip though!
And of course I love coming here to read about peoples trips, upcoming changes etc!