There's a lot really. Kills/top fragging isn't everything. Team morale does a lot to garnish wins. Be super positive with your team, at the beginning of the game, set the mood. Tell your team hello, establish a good vibe. Even if your team is trash, just tell them "Hey man, nice try! All good, we'll get it next round". I went from silver 4 to LEM so I know pretty much the entire spectrum of players. Team morale is definitely at the top of increasing your rank and wins.
Team morale aside, knowing maps and strats. This is huge. 1 person on the team having amazing game sense and strat coordination, as well as, knowing great smokes and can entry frag can definitely put you on another level on any team. I'm speaking from a solo Q perspective (I only solo Q). This is why you want your team morale to be up, because then they will be more open to listen to you and work as a team. You could be a bottom frag, but if you have great strats and calls (and established a good relationship with your team), this could be the one thing that helps your team win and leading to ranking up.
There's going to be straight up bad players with bad attitudes, just mute them and focus on the players who are trying to win and have fun. Also, if your team isn't listening to you, just play with them. Don't go off and do your own thing because you think their strats are bad...just be there to support them the best you can, despite thinking what they're doing is terrible (which may be but, you can at least try to help them win even if its the worst strats)
There's just a ton of little things honestly. The best advice I can give you from a solo Q players perspective is try to be better at becoming a well rounded player. You can top frag all day but at the end of the day, CS is a team oriented game and one player rarely alone takes a win for a team. You'll definitely notice your nova top frag lowering as you increase in ranks while you develop other personal skills and become a bit more humble. Trust me at LEM it's a lot harder to one tap people because movement becomes a much bigger factor. Also, practice getting good at entry fragging, its a powerful tool to have in your arsenal. Know on maps where people typically sit, pre-firing will be easy.
I could go on and on. Been there tho man, ask away.