If you’re straight (heterosexual), don’t force yourself to like the same gender! You can try, but it won’t work because you can’t choose who you’re attracted to. If you’ve already found a girl you like, skip this step. To find a bisexual girl, visit your local LGBT community centre.
Unless she’s your best friend, but if you’ve just met this girl get to know her better and try to become her best friend.
If you really got to know her, ask if she’s bi or lesbian. Don’t do this if you think she doesn’t trust you enough, be patient, she would open up if she trust you, once you earned her trust ask her this question. How you gain her trust is tell her a secret, not your biggest one but one you feel comfortable telling her. Don’t make it seem like a big deal, just nonchalantly ask her.
That’s part of liking each other, dating! If you feel like she’s your bestie now, ask her out casually like “lets go to coffee shop” or take her to a basketball game! Find out her interests first, then take her somewhere that fits her hobbies!
Facebook, Twitter, Snapchat, Instagram, etc. Ask her to add/follow you on a social site, you can know her better this way.