Shoot at night.
I know that's a bit flippant, but time of day, weather conditions, the background through the window and position of sun will make a difference. Apart from that, flash or a reflector at least will help balance the light.
I suppose another question to ask is whether you do in fact want to shoot straight at the window, which ordinarily will leave you pretty much with a silhouette (or blown window), or to shoot sideways, across the window, taking advantage of the window light to illuminate your subject from one side, thus creating shape and depth. You can use a reflector inside the room for fill if you need to.
Bridal prep shots may give you some ideas. Try having a look through a few weddings by Aleksandras Babicius to see if you can find some examples. I'm sure there will be some -
http://meninenuotrauka.lt/
More possible ideas -
http://www.google.co.uk/images?um=1...=1&q=bride+window&aq=f&aqi=&aql=&oq=&gs_rfai= and here -
http://www.google.co.uk/images?um=1...q=window+portrait&aq=f&aqi=&aql=&oq=&gs_rfai=