For me, since I don't have any idea of their personalities. I go for their looks. Preferably if they have long and red hair, and a dazzling face. I would go for that route immediately XD
Definitely his looks first, then how he talks (or personality) lol but I always follow the route order from walkthrough. So, I'm just eyeing him until I get into his route lmao
If there's no walkthrough, I'll play the cold LI with silver or black hair first lol
If there is a common route or prologue i choose the one that i liked/ stood out the most, if not then i too go on looks the one i think looks the most attractive lol