How can I start playing DPS?

I want to play DPS now that I climbed to Plat just spamming support, but my aim is shit tho, its gotten a bit better and sometimes I can do good with Mantis and delete someone with Rocket when they try to flank, but I'm just lost tho, I want to play something like Starlord mainly but I don't know what I can do to really improve my aim, I'm playing in pc btw