Essentially Di55ec7ion is right. The scoring is simpler than a lot of people make it out to be. Just your four categories and getting them as high as you can in as short a time as possible. Lengthening the game is not necessarily a bad thing. As long as you are still raising one of the components of score your score will continue to rise. At a certain point though no matter what you do it will not be all that beneficial to keep going. An example is the last game I did. On Dec 22 2229 score was 651500,
On Dec 22 2230 score was 757750, on Dec 22 2231 817,750, and for the final last year 852,750. So you see the diminishing returns as the game kept going and at a certain point there really wasn't much more to be done to try to increase it any further, nor was it worth it to keep going for what would surely be less than another 25K gain.
It really just involves taking the galaxy as quick as possible in order to spend the rest of the game developing/building score. In the above game I had 465 total planets, by 14 months in I had I think 427 of them and before the end of reported year one(or shortly thereafter) had 464 planets. After that it is taking the most efficient and quickest path to getting the scoring components up. Which that part of it is another entire conversation within itself

. Not sure if this helps all that much, but just trying to give an idea of how it works.
One note; Technology score gives by far the least return for investment. Most of the top scorers have stopped pushing for tech altogether and just focus on getting the other three cat. up. In my game tech score was maybe all of 35K, while things like military ended up in the 12Mil. range. After a initial all labs strat for the first few months I built over any labs I had and never built another. When you have most the galaxy just the tech from focus on that many planets will still have you finishing the tech tree within a few years anyway.