Any tips on getting better at shooting?

I play on a PS4, l've played other games that involve the usage of guns and I wouldn't say l'm that bad at those. But I'm on chapter 6 of RDR2 and I'm genuinely shocking at shooting. It might be the fast paced nature of the missions, but I suck. I'd love to platinum the game on my next play through when I'm not doing everything so in depth and with these skills it's not looking likely.