The best suggestion is to push the tougher to get ADRs toward the end of your trip if you can, and then make sure you book them first when you start making reservations.
For example, if you are wanting to do Sci-Fi, Oga's, Beaches & Cream, BOG, etc., you are much better off to try for those on days 64, 65, 66, etc. than hoping to hit one of them on day 60.
Also, if you are wanting to do something like Biergarten or Shula's, get your other reservations in first, then go back and add those easier to get ones on the front end of your trip.
We are a party of 8 going first week of June, and ended up with reservations at Boathouse, Shula's, Biergarten, Liberty Tree Tavern, Crystal Palace, San Angel Inn, Oga's & Sci-Fi (same day), Be Our Guest, and Chef Mickey's in that order - so it can be done. Of those, only Sci Fi (3:00 pm) and Boathouse (4:30 pm) are at times that are not really close to what we wanted. I am still checking for different times on those, but what we have will work if necessary.