Thought I'd give this thread a nice big bump because I just did my own yesterday, and although it was a bit of a disaster (she wasn't interested in the cupcakes!), the photos have turned out really well It did take some smooshing-icing-on-her-face for the cute and messy photos, but they look pretty good.

One tip I'd give anyone who wants to do a cake smash is to make the "smashing area" very big. Not only did Amelia keep trying to escape, I had to get rid of some good photos because you can see the edges of the blankets I used as a backdrop. I cropped a lot, but some couldn't be used because I wanted the colour behind her...
If you'd like a bit of help "extending" those blanket edges I may be able to help