Reddit mentions of American Cinematographer Manual, 9th Edition

Really what you REALLY need is experience. Equipment is rented by the production, so your primary tool and area of expertise as a 1st AC is rarely going to actually be in your hands unless you're on the job! Start off as a camera intern, you don't need anything for that execpt for enthusiasm, hands to hold and feet to run. Fuck dry erase markers, that's not what ACing is about! :-p

(though in honest answer to your question the essentials are: 1 soft tape measure, 1 hard tape measure, at least three colors of 1 inch gaffers tape, ink pen, dry erase pen, lens cleaner, multiple colors of sharpie with doubles because people keep stealing them, dust can, lens brush, tweezers, mini-screw kit for those tiny camera screws, gloves that let your hands move but are made of a non conductive protector like leather, velcro tape, and a mini clipboard for camera log if logs are being done. And a belt holster to hold it all in, available at army surplus stores if you don't want to get an expensive la-di-da Setwear one.)

You can use this book to start out and then graduate to the bible

American Cinematographer Handbook.

Costs bucks but totally worth it.

http://www.amazon.com/American-Cinematographer-Manual-Ninth-Edition/dp/0935578242