If you're thinking of doing your own concrete countertops, I highly recommend the Cheng book (available on Amazon) from Taunton press. It's pricy, but by the time you get done building your counters, it's a small price to pay. The book gives great step-by-step instructions, from mould construction, to mixing, to pouring, to finishing, and trouble-shooting.
We're in the process of building our first set of counters, and, using the book, we're having great success after casting a single test piece. And that's with really minimal experience (deck footings, mostly) with concrete in the past.