hey Spanier,
the way i've always done it and they way i've read the most commonly is to do the blocking and "main animation" first, they way i look at it is if you can make that resemble what the character would look like then your more then half way there, people wil pick up on the attitudes/ mood of a character more from the body and actions then the lips - you may also want to do the emotional work here such as the subtle changes in the eyes, cheeks and mouth.
Also you may want to look at previous 10 second club winners who've not used genri but the other common model on that site that has very few lip positions but they've still won because their characters resemble the attitudes and emotions the characters in the sound clip have
hope that helps