I've only recently learned to keep even a bit of my coolness when falling in love. Someone falling in love too fast, being too excited about the other, etc.. makes a bad and a good impression at the same time. I think I've done it. It's nice for a person to feel instantly loved, but it raises some questions.
Well, I'm excited to have the company of the one I'm attracted to, and it shows. If I'm most comfortable with myself and with her, I don't hold anything out. I won't probably act very silly, but I just behave like all the time with her were a celebration. Mm, actually that is silly

But there's place for it.
If I do hold out something, I tease her a bit, won't directly appear so attracted to her, but it will still be evident that I'm attracted.
If I'm totally in love with someone, I want to share and experience everything she likes and everything she thinks. It's like having an apetite for the person's world. It's like uniting the minds. Two individuals, a feeling of unison.
Perhaps more than many others, I want to have long, delightful and meaningful conversations. Experiencing and doing everything together can even take a secondary role every now and then, if she is a strong N as well. I love it when there's a chance to make some dinner, enjoy some wine and talk. If we've planned for, say, a movie, I'd love to find conversation more interesting and go with that instead. Or visit to a dance club, a pub, or anything..
I have a painfully embarassing memory of a girl I fell in love with, who didn't return my love. Remembering that even now makes me want to hate myself. The memory and the incident is so simple - I smiled to her, and I remember her turning away in quiet laughter, communicating one thing to me - that it was laughably ridiculous for me to approach her with so obviously in love with her, when she couldn't care about it any less. I was young, but remembering this still hurts me for understanding how naive I were. Such a simple thing, so painfully in my memories. I don't hate any other memory of mine so much.
I think I've grown to avoid such situations a bit. I've noticed that altho my keen interest in my loved one is consuming at first, they would have expected direct expressions of love much earlier.. and more intimacy early on, both in words and in practice. I'm somewhat hesitant to cross the border between a casual girlfriend/boyfriend relationship and one with a more determined relationship. I still love my independence, and I find it hard to give it away, and start appearing in social functions as a couple. I've usually found it hard to discuss my and her feelings too, and to decide where to go with the relationship. Somehow that has felt akward, tho I believe that I'm up to the challenge now.
So after everything, I'd think to be somewhat avoidant, independent, playful before falling in love, and very excited, upbeat and wanting to share most of everything, when falling in love.