Hoefler & Frere-Jones have posted up a nice little article about mixing fonts - a good read through for any designer when it comes to selecting typefaces. Not having a ton of schooling in terms of the actual process of design (my education was more about deployment / implementation of design, not the creation of) it is very intriguing to see words like \"mood\", \"cheeky\" or \"debonair\" used to describe typeface choices. Overall the four techniques all center around H&FJ\'s \"Highly Scientific First Principle of Combining Fonts: keep one thing consistent, and let one thing vary.\"

Good advice indeed.