How do you keep a bouquet from a wedding looking nice after the wedding?

Okay, so I was a bridesmaid in a wedding today and I was wondering if there is a way to keep the bouquet that I got, which is made of fresh flowers, keep looking good even after the flowers die. I heard you could possibly put hair spray on the flower before it wilts so it won't look so wilted after it dies.I want to keep the bouquet because it is beautiful and I want to remember the day my friend got married...so I was just wondering what I can do to keep the flowers( which are roses) together and looking nice after they die.Thank You.