What do I need to get an s- on Poppy top lane

I've been playing Poppy for a bit less then a year and I plane on maining her alone side with maybe shen if I ever buy him and yorick. So I wanted to get level 7 poppy but the only actual S- I have ever gotten with poppy in all the games I have ever played with her was in a Ascension game and I got 9/6/21 so ive been trying to get exactly that score but its a bit hard so any tips on getting a s on a tank,and I know I may suck at poppy but I dont do crap every single game