when it comes to telling a person that they love them, thats a lot to take. before you tell first make sure that you are in complete and total love with her. also, picture youself with another girl you have feelings for and "visualize" a relationship and see if you can ever see youself loving her in the way you love this other girl. if you do decide to tell her, "drag it out" dont tell her out of the blue or in a bad setting. make sure that you lead up to it. like hang out with her and say things that will get her to realize that you might have these feelings. if she doesnt get freaked out by all of this carefully chooe your words and keep going, but if she is pulling away at all, dont make her uncomfortable, just be GOOD friends, and love eachother in a friendly way until you see a sign of any sort
hope this helps