A smart girl would be giving you hints that she's attracted to you, you would most likely know. It's not like she'll be giving you different kinds of hints than the average girl would, they actually use the same kinds of hints.
So basically... she'll be asking you questions about you, trying to talk and hang out with you, complimenting you, leaving you notes/txts/messages, when her attention is mainly on you, etc. You'll know and feel something coming from her.
i don't think the quality of "smartness" matters. I'm pretty good in school but i don't know anything else like music, gossip on celebrities, gossip in school, or things mentioned in magazines! a "smart" girl is still a girl and acts like any other girl would. she would definitely like u if u had the qualities of a really great guy.