I'm not a pro either but one thing I do know is that natural light is best. I position my cakes on a table with direct morning or afternoon light if I have time. An iPhone photo isn't bad if you have the right placement. If you're using a background, I would go with either white or black, or even a color that brings out the smallest detail in your cake.
This one was taken with my iPhone at about 8 a.m. with direct eastern light and I feel that it is one of my neatest shots. The colors look so much brighter.