I'll start by saying that our Feb 2019 to Disney was the first vacation we spent a lot on since our honeymoon - air travel for 4, many days at the hotel park tickets, $3.50 waters, etc.  But it was a great trip and we loved it.

I love taking notes, so here are some brief, hopefully helpful notes on seeing the mouse.

6 months out you can make reservations for fun princess and character experiences (I believe start time at 6am).  We liked:
*Perfectly Princess Tea
*Cinderella's Royal Table
*Disney Hollywood Studios breakfast with Sofia and Doc McStuffins

Starting with this, I did it all through the Disney app (My Disney Experience), linked to our room reservation number (we stayed on resort - it's nice being on the monorail with the Magic Kingdom - you can do that with Grand Floridian, Polynesian, or The Contemporary)

Get the app.  You gotta just do it now.  We'll wait.  https://play.google.com/store/apps/details?id=com.disney.wdw.android

2 months out, you can start booking your Fast Pass.  As of Dec 2019, the timing is at 7am.   Some rides that we really needed it for were:
*Seven Dwarfs Mine Train (this is amazing - was my kids' first fast coaster and they loved it)
*Space Mountain (Lulu went on it!)
*Thunder Mountain (lots of fun!)
*Soarin' around the world (Epcot)
*Toy Story Mania (really fun target shooting game at Disneyworld Studios - though Slinky Dog looked good too)

You can go from the airport right to resort with Disney's Magical Express.  It's great - do it.  They take your checked bags right from the plane and they magically show up in your room.

Once in Orlando, we enjoyed:
*Rides in the morning - if you're staying at one of those hotels, you can show up at 8am and the lines are short; it's also not too hot then
*Eating at our hotel - we loved Gasparilla Island Grill (we also picked up snacks from there - hard boiled eggs, apple slices, carrots)
*Napping during the day
*Pool, then park and rides (note that if you spend your 3 fast passes in the morning, you can sign up for another tough to get ride at night - refresh by clicking the time button on the app)
*Watching the fireworks (at 8pm)

We also really enjoyed this food:
*Dinner at Be Our Guest (with the Beast - the food is amazing.  And we got to be late for a Fast Pass with the receipt from there!)
*Citrus Swirl ice cream in Adventure Land

Honorable Mention rides (worth doing once):
*Tea Cups (so much fun for our family!)
*It's a Small World ride
*The Carousel in Fantasy Land (Prince Charming Carousel)
*Peter Pan ride
*Dumbo and Aladdin Flying Carpet (very similar rides); spinning 15 ft in the air.
*Barnstormer (roller coaster for little ones)

We heard great things about, but didn't:
*Book a VIP Tour (front of line for rides, but super-expensive)
*Animal Kingdom
*Ordering food on the app and just picking up at the window
*Go to the castle just before the park opens for a daily princess opening ceremony

Other good things we did:
*Bought strollers
*Wore hats and sunblock (in February!)

Mistakes we made:
*Any time we tried to do too much
*Polynesian luau dinner isn't the best for young mousketeers
*Epcot is a lot for little ones, especially in a day with other things.  It's also not super-easy to get to.

There are lots of other resources too, like: