Practice in Illustrator ADDED COLOR
As you know I am trying to became a success in Graphic Design. I was talking to Craig asking him what I need to know or what some great practice would be and he said just pull off images off web and trace them in illustrator to get practice tracing object. Usually you draw/trace object then color then stylize.
Here is my practice with the pen tool / tracing.
Original:

My Pen trace

Colored



Thats a nice start for the outlining. Next, I would try to incoporate color into it and use layering to try and tackle the natural shades that are showing up in the photos.
Here's an online tutorial I quickly found from google that may help:
http://tinyurl.com/NiceIllustratorTutorial
Colored version .. WAY GOOD!
Looks edible, I want to eat it