We all know that HP trinkets, damage boosting armors, CTR/ASI weapon UVs, good connectivity, and great skill can get you the top score on the leader board.
But here is an idea that is out of the box. When playing LD it is tempting to spawncamp (I mean it's obvious where they are), but spawncamp heavy matches don't last long and thus you have less time to do damage (it can drop even more if the other team refuses to come out).
So, short matches where the enemy team can't even leave base severely shortens the time you have to fight. What is the solution to this problem? Allow them to cap some points, obviously you want your team in the lead (I guess). Regardless anything you can do to lengthen the time in a match will make your potential total damage go up.
1. Keep points even, if your team is behind cap or uncap a point. If ahead allow them to cap, then kill them and don't uncap.
2. Don't participate in spawncamping if your team is ahead.
Running out the clock and not reaching the score limit will give you the most time to do damage.
(of course there are infinite matches but no one will give you respect for getting a big number in one of them)
Matches in which you spawncamp don't last long because you spawncamp, they don't last long because one team is vastly superior to the other. If you don't help spawn camping, it might help the enemy team a bit, but in turn you're losing out on damage you could've gotten while spawn camping. Using strategies like that is silly because you can't get good damage in such games. It's better to wait for a new game and hope it's more balanced.