When I had my wedding banquet, I planed everything with her, except a surpise flower. Remember a surpise can't be done by yourself alone. Ask your friend or even the bride's maids to help you.
I asked my friend to hide a bunch of flower. I asked my wife to stand a bit closer to the front and I stepped a bit back and got the flower. Then I kneeled down and told everyone that I didn't give my wife a bunch of flower at all as she thought it's waste of money. Even when I was proposed to her, I didn't give her any flower. Therefore, I took the chance to gave her flower and proposed formally in front of everyone. Of course, say I LOVE HER, loudly in front of everyone.
You don't have to follow anyone about what to do, the main point is to do something unexpected and sweet. Anything you do would make her sweet.