Whenever I do an art trade or draw anyone else's character for any reason, I do a few test sketches to see of I can get the character right, or at least adapt him/her/it to my style adequatley. Then I get on with the real drawing, using these sketches and the original references for guidance.

Here are the unretouched test sketches for "Tristan" a character of ZinaCat and a subject of a contest where one of your own characters is to be shown interacting with him. the finished image can be found here.

And yes, I do work my pencils to this degree of sharpness. Must be why I take so long to do a pic. I'll have to work on that if I want to do the artist alley thing at cons.