You could give her a pretty basket, inside put some hair related things... Combs, conditioner,Bands,flat iron, spray etc. In it include a cute card stating her hair will done on that special day compliments of you. You can be clever with the basket and card.
You first have to know the bridal gown that she will be wearing for you to be able to select a suitable hairstyle. Based on her dress neckline, decide if she should wear her hair up or down and if she is wearing a halter gown, then her hair should be worn up so that she can show off her shoulders. Make sure that the hairstyle is as neat and simple as possible and you can even use curling irons, flat irons or bobbin pins to hold the hair. Check out http://www.ehow.com/how_4795317_style-bridal-hair.html for more information.