I'm in charge of making cupcakes for my sister's wedding.  I'm an amateur baker at best and have been experimenting making cupcakes using cake flour.  The texture and taste are wonderful, but the middles sink and the edges are crunchy and the tops appear gooey and full of tiny holes, more so than a normal cupcake texture.  

Please help!  What am I doing wrong?  

Sounds like too much liquid.... or not enough flour.  Are you using a recipe calling for cake flour or just subbing it in?  Cake flour has less protein, so it creates less gluten.

Oh and not all cake recipes make good cupcakes.  I have a key lime recipe that makes wonderful cakes, but the cupcakes come out about how you describe, so I have to change up the recipe if I want cuppies.