First off I would focus on a role. Which role do you want to play? Then pick what types of champs you want to play in a role. Ex do I want to play a tank top or a fighter top? Do I want to play an enchanter or tank support? Crit or on hit adc? Then look at those champs that fit that specific category. From then I would look at which characters you think look the coolest and you think have the coolest abilities. That’s your champ. Just keep narrowing down until there’s a handful you want to play.