We went in July 2013 (so before Ratatouille), and it's been our only Disney Park to date.
We took the train from Paris and only had time for a one day visit. We weren't as prepared as the advice you've been given above, but did grab a few fast passes and wandered around a lot, knowing the Park hours were very long in the middle of summer. Mrs and son (10 at the time) aren't coaster people, so this was more of a balanced family visit as opposed to adults wanting to tick off the bucket list thrill rides.
We lined up at the security screening point before general public opening. We went straight to DLP, then scooted to Discoveryland, grabbing Fastpasses on Buzz Lightyear. First was Star Tours (20 mins wait). I then went on Hyperspace Mountain (single rider). We walked through Nautilis (take an extra moment in each room to see the story with the squid). We used our fastpass on Buzz Lightyear (shooting dark ride), then ate in that area of the park (Hyperion, as it had a show on while we ate).
We then wandered through the castle and into Fantasyland. They did Dumbo & Carousel. Peter Pan had a long wait so we went into Adventureland. We wandered through Pirates Beach, Adventure Isle (such attention to detail! Yeah I know, Disney) and a 30-45 minute wait for Pirates of the Caribbean.
Our plan was to do WDS before dinner then return to DLP for more atractions and the fireworks. We made our way back to the front of the park through Frontierland. My main regret is not passing Thunder Mountain early enough in the day, I think all the fastpasses were gone by then. Lines were well over an hour. I took my kid on Phantom Manor (45 minute wait but really worth it). We entered WDS and split up. I went on Rock n Roller Coaster (15 mins), they did Art of Disney. We met at Armageddon (Walk-in so we did it), and they piked on Tower. Crush's was under maintenance (Ratatouille wasn't to open until the next year). We did some shopping in there as well. I'm sure we did more in WDS, but it escapes me at the moment (we missed the last Tram Tour of the day by a minute.)
We had dinner at Earl of Sandwich in Disney Village, but seriously most places looked pretty good. Remember this was summer, so there was plenty of daylight hours to go. @themagician I'd suggest eating on the go during the day. Sit down brekky before Park opening sounds like a good idea.
Back into DLP we returned to Frontierland, and again Thunder Mountain had over an hour wait. We continued back into Adventureland, and again split up. I did Indiana Jones et le Tempe du Peril, Wife and Son Robinson Tree house. We passed back into Fantasyland via the Castle, ensuring we visited the Dragon. This part of the day was for the family, so they wandered Alice's Labyrinth before dragging me onto It's a Small World. It was twilight by this time (after 9:30pm), with the fireworks not due to occur until about 11:00 iirc. We slowly made our way back past the Castle and Main Street, and jumped on the Train back to Paris.
This skims over a lot of things we stopped and looked at passing through and between Lands, including shops, snacks, meeting characters and the like. As @Santa07says, be prepared for your plan to be thrown out the window. But make one or two nonetheless.
It was an amazing day for us, including having a drama on the trains (we had to change lines on the way back, and found nowhere to insert our Metro tickets leading to the conductor/ticket inspector almost having a go at us until she realised we didn't speak enough French to explain ourselves) and at our end station, emerging from the Metro at Republique into a concert played by Bastille (singing Pompeii at the time!).