[nichpr]

Shots like this demand pin sharp focus across the blossom unless you are just trying to show the stamen. One effective technique to accomplish that is to arrange the subject and your camera so that they are both in the same plane - or that the face of the flower is parallel to your camera body. This will put the maximum amout of the flower within your field of focus (eg Depth of Field).
Another method is to use a smaller aperature (big f number) that will increase your depth of field. Don't be afraid of small aperatures and the longer shutter speeds they require - that's what tripods were made for. I've shot many pictures like yours at f32 with a 20 to 30 second shutter.
Keep shootin' and experimenting and posting here so we can share your progress.