I really want to practice my decorating skills but I am sharing a kitchen with someone right now and so I really hate making all the messes. I was thinking about getting a foam cake to practice on but have never really seen much about it. Has anyone else used the foam cakes to practice on??? Did it work out good for you?

I am still going to bake cakes and decorate them when there is an event or to practice molding cakes but I can't do it every week etc.

Also, are there any tips for using the foam dummies?

I have used dummies. I made few display cakes with them. If you are going to cover it with fondant, damp the dummy with a little bit of water. And when you are finished, soak in warm water and the fondant should come out easily.

Thay is an inexpensive way to practice. You can cover them w/press & seal plastic which will allow quick & easy clean up for the next type of practice you want.
The are other ways too: turn your cake pan over and practice on it. Use a cake circle (for tops) or stack up a bunch of circles into a 'cake' then cover w/foil or such.
I prefer styro best