If you aren't sure if you want to wear your hair up or down, compromise with a sexy half-up look. There are countless combinations of hairdos in this style -- you can wear it curly, straight, braided, twisted or even with a pouf in the back. Best of all, you can pull off these hairstyles no matter how long or short your hair is. The secret to keeping your half-up 'do looking great all night is using lots of product. Use a smoothing serum to keep away the frizz and finish with hairspray. Rebecca Romijn wore her hair in a stylish half-up finished with two white roses when she married Jerry O'Connell in 2007.