I have found a few sites that have tips on how to dress like Bella. Check them out!
http://insidebellascloset.wordpress.com/clothing-reviews/betsey-johnson-replica-alices-closet/
Surprisingly this site was more helpful.
http://www.collegefashion.net/fashion-tips/how-to-dress-like-bella-swan-from-twilight/
http://www.gurl.com/2012/11/15/bella-swan-outfits/
This site was very helpful too.
http://www.bellaandedward.com/style/bellaswan.php
And just to show how Kristen is alot like Bella, look at the two styles below.
http://hollywoodlife.com/2012/10/04/kristen-stewart-bella-twilight-style/