Everything you do (in life and as an entrepreneur) should start with an underlying passion. If you aren't pursuing the things you're most passionate about, you're doing it wrong (or just for the wrong reasons). IMHO.
So in that regard, I'd highly recommend reading Simon Sinek's "Start With Why". If you're not up to reading a book, just Google his TED talk as a start.
I'm sure you'll get all the conventional startup books on this list, so I'll share some of my favourites that might not come up.
I'm a huge fan of the following:
1. How To Win Friends & Influence People by Dale Carnegie
Yes, this one is old. Yes, it's a thick read. And yes, the principles are more applicable today than ever before. Especially if you want to learn how to work with people and get them to do what you want (the honest and fast way) to get remarkable results.
2. Sho-Gun and The Noble House by James Clavell
These are 2 amazing books that explore everything you'll experience as a pioneer. The beauty of them is that they're grand adventure stories, which makes for a fun and gripping read. (Because let's face it, sometimes you just need to relax but you still want to expand your mind. This is the perfect book for that mood.)
FYI: There are actually 6 in this saga, but these are the top 2 I'd recommend for anyone who wants to start a business.
3. Marketing Myopia by Theodore Levitt
If you're confused about marketing, read this. It's short (it was actually an HBR article that was turned into a mini-book).
4. The Corporation by Joel Bakan
If you're an idealist, read this. It explores the dark side of starting a venture, and the real purpose of a business entity. A scary read.
FYI: It excludes the modern "people, planet, profits" concept, which I'm a huge fan of.
5. ReWork by Jason Fried & David Heinemeier Hansson
This one will probably come up, but I want to make sure it does. It provides a great framework to understand what you actually need to do to move the needle. Every page I turned I kept thinking, "Yes!"
Good read, especially if you're coming from a more corporate background. Plus, it's a glorified picture book (you'll see).
6. Made to Stick by Chip Heath & Dan Heath
One of the first "entrepreneur" books I read. Love the stories Dan & Chip showcase, plus they give you a great framework to create sticky ideas.
7. The New Digital Age by Eric Schmidt & Jared Cohen
This is new in 2013 and a *MUST READ* for anyone doing anything digital.
Best of luck!
The obvious ones for me are Simon Sinek's 'Start With Why' and 'The E-Myth Revisited' by Michael E. Gerber.
More on the marketing side, 'Purple Cow' & 'All Marketers Are Liars' by Seth Godin. Actually, for that matter, anything by Seth Godin.
It depends on what your goals are for your business and its scope, but if you have big plans, I HIGHLY recommend these three:
BOLD: How to Go Big, Create Wealth and Impact the World by Peter Diamandis and Steven Kotler
ORIGINALS: How Non-Conformists Move the World by Adam Grant
VENTURE DEALS: Be Smarter Than Your Lawyer and Venture Capitalist by Brad Feld and Jason Mendelson
Personally, I'd suggest for you to read the E. Myth by Michael Gerber, Secrets of Closing the Sale by Zig Ziglar and F.U. Money by Dan Lok.
You'll get a healthy dose of actionable information alongside a good serving of perspective reality.