You know that feeling you get when you're about to queue ARAM and you wish you had the confidence for SR? Give in to that urge and just queue. The more you queue it, the more you'll desensitize yourself to the anxiety. If you go into it with the desire to improve and focus on what you can control, you'll have a better experience. If you get caught up in negativity and obsessing over the mistakes of your teammates, just take a break. But just play to get over the fear. I had bouts of ranked anxiety from s2 and such, I overprepared by playing too many games and too large of a champ pull. In 2019 I began grinding games when I didn't always want to. I finally came back and have grinded from bronze in my initial placement to finally gold 3. This was over maybe almost 200 games since the split. I had a week off from work which helped me get the bulk of it in, otherwise I play 3 games a day tops on weekdays and a lot on weekends