The main thing that jumps out is lack of map awareness i.e. you don't seem to know where enemies "might" be and going routes you should never go by unless you know that your team are controlling the roof.
Aiming didn't seem too bad to me and you seemed to be able to control recoil and burst fire well enough but as always, well placed headshots will drop someone much quicker.
- use the bottom mini map, such a big advantage, if someone fires without a suppressed weapon they will show on the mini map, you missed out on quite a few easy kills and there was one camper at the very edge of the map, probably shooting people on the roof when they came to the edge
- go for the flags! When you see your blue A, B, or/and C flashing, that means someone is there, honestly you can come in the top 3 quite easily if you just cap and defend flags
- don't stay in the open and most certainly don't run along the side of the map where anyone on the roof could easily kill you, before going out, aim down the sight whilst scoping the roof area
- to take the roof back, you have 3 ways, elevator (usually someone guarding it or/and with c4 lying there), 1 ladder at the side of the sign where the elevator is (can get up via the glass/metal bar ramp way and 1 ladder at the other side where the other glass/bar ramp is brought down
- aim down sights when going around corners and as you said, try to stick to walls/cover and only peek out as much as what you need to, why give your enemy more to shoot at? And if you think someone might be around the corner, scope around whilst checking the area
- remember to hit q a fair bit as it will show where enemies are, even if you don't physically see someone
- if someone is camping around a corner and he sees you plus fires at you, don't peek from the same corner, go to another place or flank them i.e. the noob at the corner of B lying down that you tried to noobtube
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, if that were me, I would probably have gone around to the right through A or run past the crates and go to the blown up truck (only that option if your team had the roof though.....)
- you don't really need to aim down the sight when someone is very close to you, should get the kill by just hip firing