CS:GO Skill?

Try recording yourself and see what improvements you need. You cannot judge yourself while you focus on your gameplay.

I still remember the old days when my brother used to play the old counterstrike online.
You are playing against other people so your chances of winning fluctuate with their skill and perception versus your team's skill and perception as well as communication and just blind luck...
so, only thing you can do is practice

What is your rank? Do you strafe as you run? Do you stop, crouch and then shoot? Do you use burst fire or do you just hold down the trigger? Is your mouse sensitivity set correctly for how you like it?

Lots and lots of factors go into it lol. Try to pay attention to when/ how/ why you die. Look for what you're doing wrong. Did the guy get you as soon as you peeked? Maybe you need a flash or a smoke if someone on the other team is doing a good job holding a corner with an AWP. Focus on the replays and look for anything you're doing wrong. Sometimes the other player is just better, and thats when you see what he is doing and try and incorporate that into how you play.

I still lose about half of my competitive matches.

That's how it should work.
(let's pretend there are no smurfs and hackers) if you win more\less then the half you are matched with the wrong people.

I was Silver Elite after 10 and Gold Nova 2 after 13 wins. What helped me get there was playing with higher ranked people. I didn't get boosted, but I played with people that just had high ranks and didn't care if we lost because of me. It certainly helped tho because you adapt, thus increase your skill more efficiently. After I quit playing with them I realized how easy it was with people on the same rank as me.
Also knowing the maps you play on is important. Knowing some basic strats, where to smoke, how to do pop flashes and pre-aim etc.
The most important part is your team tho. Either you play as a team or each individual is really good. Otherwise you lose for sure.
So playing with a consistent team is an advantage. I figured it's a gamble otherwise, because sometimes you get into a team full of trolls and just lose.

100 hours is more of a super new right :3 If you lose half of the matches means you are on your right place, people advance if they have like1.3 winratio.

Do you communicate with your teammembers and use tactics?

Just try to have fun don't take it too serious

Just play, cooperate and communicate w/ your teammates. If you have griefers on your team, nevermind them and just play .
Silver 2 here. just ranked up after 15 STRAIGHT wins. so yeah my rank is trash.

depends on your sensitivity(pick where you're comfortable) , map awareness, voice and message comms.

If you're wanting to get better at cs:go, i'd suggest checking out the WarOwl. His tutorials are pretty damn helpful and good. He certainly is a big reason for why i'm as good as I am now.

Link to his channel