From my brother, Mike:
I'm currently re-reading Ellen Shapiro's "Graphic Designer's Guide to Clients: How to Make Clients Happy and Do Great Work" . Although she speaks specifically to designers, I've found that a good many of her ideas would apply to just about anyone working in a creative field. Read below where she notes Ed Gold's "10 common characteristics of great designers":
THE TOP TWO
1. talent (their work flat-out looks good)
2. advocacy or sales ability
A BALANCE OF...
10. they just love their work
"A designer who can't sell an idea is probably not going to be very successful," [Gold] says, adding, "I'll go a step further. A designer who can't sell an idea will never be a great designer."