Can't get the hang of marksman rifles

I started playing for the first time a few weeks ago (PC) but I still can't get the hang of marksman rifles. Namely when trying to lead a target from a distance. It honestly feels like a waste whenever I try using one, but I get wrecked by others using it.

I do understand that skill is a part of it but despite trying to learn it, I can't consistently land shots on moving targets. Any general tips on their usage?