when she's sleeping, put your nuts on her forehead, and when she wakes up, she'll get the message
Take her on a date and whisper in her ear that you love her
Well I love my sister and all my friends, and I usually say it in a way like this: "Girl, you are the coolest goddam f*cking c*nt I've ever met. You're my comrade, you know that, b*tch?" I'm sure they feel the love.
Say it at a time she will know u really mean it. Don't let her think its to make her have sex with you. If this is the first time ur saying it, and u mean it, it will not b involved with sex. That's what happened to me anyway... It worked.
I. Love. You.