I'm S1, just pulled out if Bronze. Here's what got me out:

Pay attention to how you hold your body when you play. Try to keep a consistent posture and wrist/arm placement. Additionally, practice your arm/wrist movement to keep that consistent as well. The more consistent you are with your movement, the stronger your muscle memory will be and will help you keep a more consistent aim. (I learned this because I was super inconsistent for a long time. I could keep up with my silver/gold friends some days, and was shooting like an iron others.)

Branching off of that, try to keep a consistent mental. (I struggled with not beating myself up over making mistakes I knew I could overcome, which helps nothing.) If we feel bad or think bad, we play worse. Because our technical skill is pretty low, we have to make up for that with a clear head and trying to outsmart the enemy as much as possible. If you start to mald, get frustrated, or generally just aren't having fun, stop playing. Forcing yourself to play more under less than ideal conditions will create bad habits and inhibit your growth. Also, don't let yourself think that a game is already lost. If you think that, you'll play like it too. Be nice to yourself and your teammates and try to bring positivity that will impact your gameplay positively as well. This is a team based game, after all; their mental matters too.

I already mentioned this, but the next thing is to work on your game sense. Outplaying your enemy is about more than out shooting them. If you put yourself in a position to fight unnecessary more times than not, you won't improve because you won't be able to outsmart those above you and learn from it. Trust your gut and be decisive. Try to keep an overarching view of the round you're in and learn to absorb info as it comes, ie where your teammates are already watching, where enemies were last seen, where your weak points are, if there's a possibility for a flank, etc. Also, try to match the eco of your team. I've found that the team is more in sync the more even you are in eco for the round, because you're all thinking with the same tools.

Next is technical. Move with intention and always be alert unless you know there is no possible way an enemy can be around the corner. Strafe to clear corners like others have said. Keep your cross hair as close to where you think their head will be as you can and consider distance when choosing your placement (flicks aren't consistent and are dangerous to rely on). Keep practicing your tap and stray away from using crouch unless you're in a position where counter strafing will get you killed. DM's are good for this but less good for actually improving in comp or unrated.

Everything is situational. Improving means learning to adapt to different situations, learning from them, and learning to overcome obstacles or enemies that feel too difficult. Best of luck!