Start with high aim assist sniper rifles. I use the Prudence II. To be a good sniper you need low input lag on your display. Otherwise getting headshots will be a random thing. You will be more likely to score a headshot if you actually miss.

WhAt is input lag on display? How do know what base level is and how do you improve or change it?

The simplest way to explain it: if you have input lag you see things later than they are actually happening. It takes time for the display to process the input and display it. The less this time is the better. TVs tend to have more input lag than monitors. Research your display for input lag. I use https://www.asus.com/us/Monitors/MX279H/. With 9 ms lag its one of the best LCD you can buy.

Thanks. I use a TV which I know is not great. I'll check out alternative displays.

Believe me its the biggest factor. I cant even play other games now on my TV. Everything feels so unresponsive. Once you get used to it, you can never go back :)

Ah thank you, which sniper rifles do you recommend starting off?