I'm weird, I like to focus on secondary/tertiary characters for shipping, like roles that won't get much screentime? Like main cast characters in romance plots/subplots have plenty of screentime to show relationship development and sometimes it becomes canon. I suppose I like to imagine more or lay down a runner for greater possibility, so perhaps crack ships are more my thing? xD
There still has to be some level of amicability for me though and at least one or two interactions between the characters. For example, while watching the Hunger Games movies I thought, "Oh, wouldn't it be nice if Haymitch and Effie got together
"
Per enemies to lovers: I hate the bully/victim ship. And the only time I can really stand an enemy to lover is if the two aren't personal enemies? For example, say one is a resistance fighter and the other is just working for the hegemony. They're only enemies on paper, as dictated by their society, but really they get along if given the chance.