I have been planning my first trip to Disney since 2000

I have gone through very similar feelings at the beginning of this process!!! It is overwhelming!!!
Ultimately I think of it as "eating an elephant" - how do you do it? One bite at a time!!!
Break it down. Make lists - then make more lists

I know not everyone is a natural list maker but it's the best advice I can give. These boards are excellent sources of information but the challenge I've found is that information is plentiful - all over the internet - but it is also scattered. If you are looking at Pinterest, for example, you have to be careful that you are not reading and taking notes from a blog post that was made years ago.
The Disney website is a great source of info. I also have really found benefit to Touring Plans site. There are so many other sites and many are great I am sure.
Once you have a list of things you know you need to refresh your understanding of you can choose to dive into each one at a time.
Here is the list I used - which is extensive and not all may apply to others. Feel free to copy/paste pick and choose!
Topics to Research
Using a
Disney Travel Agent - Pros, Cons, Options, How to find a good one
Research Trip
Travel Insurance and Airline Travel Insurance - understand what it means
Setup account and learn MDE - both web and mobile app
Best Time To Visit
Best Resort to Stay At - check reviews on Trip Advisor, DIS, etc.
Room Size, Views, Location vs. lobby, elevators and restaurants
Resort Layout
Resort Amenities, Extra Activities
Discount Options
Understand Disney's daily room check policy
Which Days to Visit Which Parks Based On
Crowd Calendars
Published or estimated park hours schedule
Decide best tickets to purchase (basic, park hopper, etc.)
Research any hard ticket events available during trip dates and decide whether or not to purchase
Research Memory Maker and decide whether or not to purchase
Research things to be aware of in regards to any festivals, marathons or other events that may be going on during the trip
Understand various Dining Plan options
Understanding When/How to Make ADRs
How to Obtain Still Wanted ADRs and/or Last Minute ADRs
Understand ADR cancellation policy
Look into Open Table and what places it can be used and the cancellation advantage
Compile more detailed info on restaurants of interest
List for/by each location - All 4 parks, water parks, Boardwalk, DSRA, resort and other resorts
Review menu options to confirm it will work for all in party including kids menus
Review menu prices to estimate value on DDP or for budget if OOP
Read restaurant reviews from multiple sources - DIS, Trip Advisor, DFB, You Tube Videos, etc. Look for tips, common patterns of complaint, comments on noise levels, etc.
Understand character meal options
Decide 1st choice of restaurants for each meal of trip
Decide 2nd choice of restaurants for each meal of trip
Determine best use of snack credits in each location (parks, resort, etc.)
Learn about any loyalty programs available - which places they are good at and decide whether or not to sign up
Use published menu prices to estimate cost of each table service meal and then calculate gratuity budget that will be needed for the trip
Look into various
free dining reservation finder services
Understand mobile ordering options and practice on MDE account ahead of time
Once released, review F&W booth menus (or other festival) and plan which to visit
Understand Magic Bands - options to customize, setting up pin, etc.
Use WDW Prep Navigator to review transportation options for each journey made during trip (resort to parks, resort to other resorts, etc.)
Resarch Uber/Lyft/Minnie Van/Taxi options and download any apps ahead of time to start getting discount offers
Look for promo codes or other discount offers for these services
Research Disney transportation options, tips and tricks, alternative routes, etc.
Understand the monorail loops
Understand Magic Express - How it works, bag options, etc.
Park Layout - Locate and review park maps, parks in relation to each other, monorail loops, etc.
Understand park locations vs. resorts, DSRA, etc.
Print park maps and supplement with additional information including:
- Least Crowded Restrooms
- Park Entrance Options including less used "secret" options
- FP Kiosk Locations (these can move but many spots typically always have them)
- Quiet Places to Rest, Indoors, Covered or Shaded Seating, Etc.
- Penny Machine Locations
- Use color coding or legend to note indoor rides vs those that will close in bad weather
- PhotoPass Photographer Locations
- Best Parade/Fireworks Viewing Spots
- Phone Charging Spots
Locate and print resort layout map
Locate and print DSRA map - marking places to visit vs. taxi pick up/drop off location
Obtain and review water park map
Research touring plan options/services
Create touring plans for each park day, fitting in meals and breaks, allowing for ample travel time
Research ideal and alternate viewing spots for any parades or fireworks planned
Create overall trip itinerary from arriving at airport to arrival back home, including rest days, extra hard ticket events, etc.
Understand the FP system
Learn which rides need FP more than others
Review various methods recommended for getting Fast Passes booked when window opens
Review Fast Pass Refresh method for use in park
Look into non FP strategies for certain rides, i.e. PPO breakfasts, etc.
Determine typical FP Kiosk locations
Review rides and shows at each park for the following:
-Length
-A/C - Yes or No
-Scare Factors for little ones
-Fast Pass - Yes or No
-Magic Hours - Yes or No
-Height Restrictions
-Flash Photos - Yes or No
-Weather Procedures
-Ride Photo - Yes or No
-Best Times to Ride
-Tips or tricks about what to watch for in queue, etc.
Watch You Tube videos of rides (potentially with children) if concerned about fright factor
Research misc. daily things at each park (street performers, splash pads, etc.)
Look for info on best places to rest at each park
Understand various park touring strategies, rope drop, during parades/fireworks, extra magic hours, etc.
Understand
DAS program options
Best clothing to wear at Disney
Footwear and care while at Disney
What to pack for trip overall
What to pack in the in park bag
How to get through bag check at park entrance with minimal fuss
Stroller/Wheelchair rental options
Babysitting Services
Plan for the rain
Plan for the heat
Plan how to pack in park bag(s) to get through security quickly
Understand hurricane policies - both Disney and airline
Plan "training" needed to prep for all the walking at Disney
Plan for minor illness/injury, motion sickness, blisters, chafing or Disney heat rash
Plan for keeping little ones calm and entertained on air flights or car trip
Plan for keeping little ones entertained in line
Look into/download the Play Disney app
Plan for pin trading
Plan for CM compliment cards, Mousekeeping tips, etc.
Plan any extra Disney magic leading up to and following trip to make things more special
Look into grocery delivery options to resort
Research ways to purchase discounted Disney gift cards and how to use them
Maintain Budget Including:
-Airfare
-Airport Parking
-Hotel
-Tickets
-Dining Plan
-Any Extra Hard Ticket Events
-Estimated Gratuities - Including taxis, baggage carriers and table service, etc.
-OOP Food (extras not on dining plan)
-Souvenirs
-Travel Insurance
-Cost of Taxis/Uber/Lyft etc.
-Kennel Costs (for pets left at home)
-New Clothing/Footwear for the trip
-Specialty Items for Trip (ponchos,
cooling towels, etc.)