Great suggestions, particularly having your desired ADRs in priority order and ready to go. One other thing we did to try to improve our odds of getting harder to book restaurants was to book them near the end of our trip -- the idea being that the later they are in your trip, the fewer people have already had a chance to book that date in their 180+10 window. We got a 6:00 BOG ADR on our last night at WDW (6/13). I can't be sure we wouldn't have gotten it on another night, but my guess is it would have been less likely.