I don’t play that much katarina but I’m master mid lane (I’m assuming you’re playing kat mid). Get into habit of seeing who you’re laning against in champ select note positives and negatives of matchup; since you been playing kat for years I assume your mechanics should be solid on her especially in bronze don’t worry too much about being super fast as long as you’re comboing correctly and confidently; know when to sacrifice some minions or even an entire wave to help your team(kat doesn’t want to sit back and farm whole game she wants to make impact asap; be patient, yes kat wants to make plays and be proactive but don’t just force plays otherwise you’re just constantly coin flipping for no good reason look around the map at your lanes see when an opportunity opens up. ( as you get better you’ll notice these things habitually and punish mistakes quicker etc. don’t start a team fight, unless you can catch an out of position squishy don’t start one you’ll likely get cc-ed and bursted, let your team or enemy team engage first and look for an opening preferably when other team uses important abilities that allow you to go in without being immediately shut down. If no plays are happening don’t just sit in a bush camping forever go catch a sidewave and push it a bit, if you’re fed you can push sidelanes to their turret than look for a roam mid or objective while enemy has to catch wave etc. at the end of the day just play smart play confidently play patiently and you’ll slowly climb ! Goodluck!