I used to play MGO all the time for almost 3 months since MGS4 was released (Started with the beta). Headshots are quite easy, depends on the gun you're using, if you are more into an assault rifle like the M14, use the grip, it will increase your accuracy a lot.
I was a SVD player myself, virtually no-scoped everyone if they were close to mid-range away from me, and i had a HS accuracy of 89%, just take your time learning the recoil of the gun you're using, and how to properly line your shots.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
