I also can't play ranked yet. I'm not currently playing Annie, but I'm playing a few different champs (Poppy, Gnar, Rakan). I think the most important point is that you have to understand if/where you get tunnel vision. You are the person with the greatest potential to ruin your game.

My biggest problem in top lane, with Gnar, is that I get greedy. Gnar is my adorable little murder fluff and I sometimes overlook whether I've compensated for his mini's squishy qualities. I get worse when Mega, as I get cocky about his toughness and forget to consider his lack of movement speed.

In support role, with Rakan, I tend to overlook the fact that I have to stay alive in order to be useful to my ADC. I try to constantly shield them and even intercept enemy attacks to keep them safe. Rakan cannot take much damage and I get stomped in the process.

This kind of thing may not be a problem for you. I'm just giving you some ideas of details you might be losing during combat.