I'm going to be honest with you. No one is ever really ready for ranked. There's always chances you'll get a one way slaughter and your team loses or your'll be carried hard...
The only thing I would suggest is being able to play about 3/5 roles. Incase your favorite gets taken.
Figure out what champions you love in that role. and just practice.
Its not about how many normal wins you have actually it's how you feel ready. Is there nothing else you can do befoee?
**How are you in regard to being ready? **
How are your rune pages?
Can you do a different role if your best role is taken?
Having X normal wins..
**How are your MENTAL SKILLS OF LEAGUE? **
Many people forget things like this but. other then mechanics. league is also very mental game.
Map awareness. Many people down here in bronze don't have the best map awareness. making it a habbit of looking at your minimap subconciously every X seconds helps you to understand where your team is, and where the enemy team is..
I see you main thresh.. that's... amazing.. your ADC is going to love you and not many will contest you for that.. Anyways..
Your incharge of keeping someone whos constantly got their eyes on their CS as well as trying to not get caught out by the enemy laners.. I play ADC, and my map awareness isn't always the best.. but there are times where I look and start to get agitated about not knowing where the enemy jungler is..
You as a support, concentrate on setting up kills for your carry as a thresh, you're the one who's carrying the bot lane and capitalizing on the enemy botlane's mistakes. As well as looking at the map where you have warded.
Ugh I can go on forever and me being in bronze idk if I'm even giving good advice..
Another mental thing is..** ACTIVES** I have a problem with this.. using the little actives on my items.. I forget the items have something that can help you more.. I always forget about it and I face palm myself..
I know why im in bronze it's sometimes just hard for me to get a grasp on the mental things..
Warding I know you main support so this isn't a problem for you.. but even I when I adc or go anywhere, I buy wards.. It's one thing I got down and bit in the butt. Sometimes I still forget, but I'm not AS forgetful as I used to be..
Working together As support your're already golden.. but some people in other roles think that they can carry and hog all the kills, but in reality you can't carry something too heavy by yourself, and you need the help of one other person. So like.. If theres someone who's fed. sometimes it'll benefit you more by helping them get fed aswell. Therefore they help you carry the weight.
ALSO.. as Support you might have people running down the river with the enemy midlaner and or enemy jungler chasing them.. If you have the map awareness to spot this you can rush in to save them and perhaps turn it around to where you get a few kills, IF you kill enough of them you can then perhaps take that dragon as a reward furthering your aheadance.
Sorry.. I know there's so much more but I feel like I'm already writing a book.. Ill just stop there.. xD Sorry im bronze and this might not be the best advice.. but.. it's what I feel might help.. I know it's alot of what I still need to learn myself..