PSA to Bronze Players
As a Bronze player myself, I find many people choosing meta champs very often when they aren't banned. Just because it isn't banned, doesn't mean you should play that champ. If you are not good with Katarina, DO NOT PLAY HER IN RANKED. Even if she wasn't banned. I just played vs. a Katarina who wasn't really fluent on that champion, and it just makes me wonder why people specifically choose champs; even when countered. Just because they believe it will be an easy win. Playing a champ you're comfortable on is better than trying to out-pick the opposing laner or "abusing" a champ that didn't get banned like Sej, Kat, Annie, etc.
I found this video on YouTube, and it essentially has everything you need to know/understand.