girls like confidence its not what you say its how you say it go to her look her in the face keep the same breathing rate as her and say it in a normal tone of voice and say "I just want you to know that I think you're one of the most attractive women I've ever seen, and I'm really glad I worked up the courage to introduce myself to you" | make sure you change it to match the situation.
say that you are always thinking of her and would love it if we could spend some time together and do some fun things cuz you think that the two of you can have a lot of good times what do you think baybee
honestly, in your own words, when you are ready. don't worry about flowery words, don't practice, or it will sound fake. just simply be you. if she loves you back, it will be memorable and romantic to her.