Tomorrow a girl friend of mine is gonna tell the girl I like that I like her.

Uhhhm , Yeaah there is deffinatley a better way :
Try : Telling the girl about your feelings yourself , instead of having your friend do it .
Having your friend do it , is not as meaning-ful , and basically means nothing.
Soo , You should deffinatley forget about the plan of ur friend telling the girl you like .
Instead , tell the girl you like yourself , and tell her how you feel .
Gaurentee she will like that .

It will mean more if it comes straight from you.
Because otherwise there is always the questions of, "well what exactly did he say?"
And then if she likes you back, chances are the next time (or maybe more times) that you talk, you won't really know where to begin and it can be a really awkward situation.
Just tell her yourself. What do you have to lose? If you think about it; nothing. If she likes you, there's possibilites for things to go great. If not, you haven't lost anything at all..you're in the same spot you are now, only you know how she feels.

why would you have your friend do it? this girl is gonna be like, "wtf? why couldn't he tell me himself?" if you feel shy, then you're probably just afraid of rejection, but you can be rejected either way, even if your friend is the middleman. personally, I think you'll have a better chance of success if you do it yourself because otherwise you kinda come off as being sketchy.

Stop your friend from doing so. Personally I believe a guy likes a girl he should show it and go talk to her, Sending his friends to do the job for him shows his lack of confidence. You don't have to be shy, If you try and it turns out fine, Then good for you but if it didn't turn out to be the way you wanned it to, Then at least you were man enough to show you like her.

There is a better way for this girl to find out about your feelings and that is if you tell her yourself instead of having your friend do it.

You should tell her yourself instead of your friend because the girl will think that you do not have the balls to ask her out and that may be turn off. Also if you ask her straight up you are going to put the pressure on her and she will be more likely to say yes since it will be very hard to say no. I would tell her before the other girl either in person or through the phone. Good luck though.

If you can you should tell the girl you like in person. Don't let someone else do it because I can't imagine that going over well.

Beat your girl friend to the punch. Go up to the girl and say, "you're probably going to hear something from so and so. She found out that I liked you, and I thought that it would be better to hear it straight from me. But I think you're really cute, etc. So yeah, I just thought you should find out first hand"