What I do is:
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Decide how many days you want to be in each park. We are going for 9 days next Feb, and the most likely split will be: MK 2 days, DHS 1 day, AK 2 days and Epcot 3 days, as this is what suits our interests/preferences. That gives me an overall shape to the holiday, and leaves one day for mooching about -DTD, mini golf, swimming, etc. or, if it comes to it, a swap day to secure ADRs/FP essentials.
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within that frame, work out which restaurants we might want ADRs for, as obviously it makes sense to make ADRs for the parks you are in/near. Also factor in any major plans, eg it is dd2's birthday when we are there, and so MK is set for that day (given what she wants to do).
When released, check out busy day guides - I shouldn't have to wait too long for the Feb 16 guides to arrive in the Dibb, as they already have up to Jan, or I might use touring plans/other sites historical info as a guideline. Work out a rough daily guide along with ADR wants.
The main thing, I have found, is that ADR availability rules (in our case - we defintiely want a lunch ADR each day, as it breaks up the day for us, and works in our situation) and so we phone up at appropriate point with our list of wants, but plans may have to shuffle at that point if no availability, especially if there is a must-do ADR, such as a character meal. I haven't found I have to switch my park days, normally, but may not get eg CRT for the first MK day in the holiday, but do get it for the second - more critical this time around due to dd2's birthday, but if we can't, then we can't. She has given me her wish list for what she wants to do in the day, but we'll have 6 months for her to get over the disappointment if we have to switch days around 
It is defintiely more Art than Science, as there are so many variables. But it is possible to get it done. It feels more stressful than it should sometimes, and the main thing to remember is that it is a holiday! Pretty much all of it is good, and so if plans change then they do, if you can't get one particular ADR, the world isn't going to stop turning, there will be somewhere else you can try.