Originally Posted by ilithiya
Mine would be that a stiff putty/spackle knife (3"-4") is much easier to use for smoothing the sides of cakes and to make sure that there's a good, sharp edge on the bottom of the cake where it meets the board. (The rounded tips of the spatulas somehow leave ridges or indents, IME.)
I love this method but I use an actual mud knife that you buy at the hardware store. Bring it home and clean it up really well first of course. This is how Alton Brown does it on the food network.