advice for competitive

First, you need to understand the basics of CSGO, if you think you are ready for MM and believe you are good enough to rank up, you can start playing.
Don't play solo, most of solo playing are made by fraggers and KDA players, you will get jebaited a lot, and people will simply die trying to frag. With a full premade with the same menatlity, can grow together an rank up quicker.
If you want to take it up a notch, maybe you want to start playing with a premade with higher ranks if you are feeling confident, its easier to rank up that way, becasu MM fixes your elo accordingly, getting you more elo than the average games playing in your rank. Its a double edged sword becasue as it gives you a boost in your grind to rank up, it gives your teammates a penalty making it easier to derank and really ahrd to rank up.
I already won games and deranked and i already ranked up in a win/tie.
Play a lot of Deathmatch and FFA to get your aim and reaction on point, always warmup for like 15, 30min before playing and if you want to go the extra mile, play FFA Only headshots for that crisp clean taps. Play with Deagle to see if your aim is on point since its a really skilled weapon, play AWP to train your reflex and flicks and play m4 for spray controls and ak for taps.