Some people subscribe to various websites offering touring plans and crowd level predictions and find them helpful. I think they could be, particularly if you plan to visit WDW during peak holiday (most expensive) periods.
We're more casual. We note the park hours and event times for each day of our visit and update them monthly until about the last month. Then they're updated weekly, until two days prior to our trip. That's the final update. Don't have time to do it again until after we arrive at WDW! *LOL* And then we can easily update the information using the resort CCTV.
We plan ADRs (we're minimalists--we don't have TS ressies every day and rely on a combination of QS and fresh food options (fruits and veggies) at the resort food courts--based on the primary park of the day (usually we have PH, but not always) to minimize the amount of time spent traveling.
If you click on the subjects on the blue bar at the top of these forums, you'll be taken to WDWinfo.com, which is the website associated with these forums. Or these forums are associated with that website--however you want to view it!

In any case, there is a lot of good information available!
You also can check out allears.net, which was one of the first websites (allearsnet.com at the time) I discovered when planning our 2003 WDW visit. They have a newsletter you can subscribe to, as does mousesavers.com.
As others have noted, the published guides can be useful, as well. We haven't used them, but we visit WDW for 10 to 12 nights at a time, so we have the luxury of not having to rush through everything.
Research as much as you can. Plan four or five attractions in each park that are essential to your family/group, with others that are secondary. View park maps to see where the attractions are located and develop a basic plan to avoid criss-crossing the parks. It probably will happen, particularly if you're determined to go on specific attractions that have long wait times and/or require FastPasses, but you want to minimize it as much as possible.
The best way to enjoy your WDW visit is to relax and not expect to be able to do everything in one trip. While WDW changes over the years, it's been there since 1971 and it's likely it won't be going anywhere in the near future!
