My name is Sharon Milne and I'm a vector artist who specialises in vector art. So much so, I'm the Editor of Vectortuts+ (the biggest and best vector community website on the net!). I've been creating vector art for over 10 years, over 5 years professionally.
The work I take on freelance is mainly vector portraits of either people or animals and it's not uncommon for me to receive bulk orders for companies commissioning portraits of their staff, a recent job I created 20 portraits all in the same style!
I create them all within Adobe Illustrator using only vector tools, which means it is 100% scalable for print or digital displaying. The files are organised well so should you know the program, you should find it easy to modify simple aspects such as hair and eye colour.
I work from photo references to create a realistic like for like appearance in the final portrait and can modify/add to portraits anything from a change of clothing, to wild and wacky hair styles.