What should i do? I need some help please.?

Well, their are these two girls at school that are my friends, and i find them pretty attractive, one is Martha and one is Irene, and i was set on Martha but she wasn't here for school and i had a lot of time with Irene so I don't know who to shoot for. I feel I like martha more but it seems Irene is so much into me and i don't want to break her heart. Irene seems not to be so shy, as Martha is. I was eye flirting with Irene in cl a lot today, and she either just keeps staring into my eyes or tries to look away and hope i don't notice, but whenever we hang out she seems to talk a lot more and not be shy around me. Martha on the other hand, she is very shy, whenever I eye flirt with her, she looks away immediately, i pretend i'm looking at something but i just look at her eyes to see if she looks then i look at her to see her reaction. If you guys could help, that would be wonderful.