When you've fallen in love with a friend, the best way to handle it is to be direct and communicate your feelings clearly. Tell your friend how you feel about her, don't pressure her to reciprocate your feelings immediately, and see where it goes.
There is nothing to be gained from sitting on your feelings and not acting on them. Left to stew, such romantic feelings can become bitter. Remember that there is nothing inherently wrong with being attracted to your friend. Presumably she has lots of great qualities, which is why you're friends to begin with. Don't be embarrassed about your crush or act like it's inherently a complicating force in your friendship.
An unreciprocated crush does not have to be the end of your friendship, either. If your friend does not reciprocate your feelings, it's better to weather the temporary awkwardness of being turned down and then to resume your friendship. It's entirely possible to voice your attraction in a calm and reasonable manner, be turned down and continue on as friends. However, this is only possible if you're able to move on emotionally and look for someone else to be romantically partnered with. If you're waiting for your friend to come around and staying friends for only that reason, it may ruin the friendship.