According to the Pathfinder Reference Document:
A wizard begins play with a spellbook containing all 0-level wizard spells (except those from his prohibited schools, if any; see Arcane Schools) plus three 1st-level spells of his choice. The wizard also selects a number of additional 1st-level spells equal to his Intelligence modifier to add to the spellbook.
The Pathfinder Roleplaying Game has 20, 0th level spells (10% of the average spellbook). When you add in the spells from the Advanced Player's Guide and Ultimate Magic the total rises to 21 (admittedly not huge)
If we include 3rd party spells (and frankly why wouldn't we) Rite Publishing adds another 101 - 0th level spells, Headless Hydra Games adds 30 more in Eldritch Secrets, the crew at 4WFG must add at least another dozen in the Book of Arcane Magic, Book of Divine Magic and Inkantations, plus the spells from the other licensed publishers at Paizo's site and Rpgnow.
So with the Pathfinder Ruleset and three 3PP publishers I need over 1 1/2 spellbooks just for my 0th level spells. Obviously even for a kitchen-sinker like myself that is not going to work. So for new wizards I'm suggesting this:
A wizard begins play with a spellbook containing ten, 0-level wizard spells (arcane mark, prestidigitation and eight others that are not prohibited), plus three 1st level spells chosen by his master (see below). The wizard also selects a number of additional 1st level spells equal to his Intelligence modifier to add to the spellbook (spells may come from any of Paizo or 3PP Pathfinder compatible source).
The spells that the spellcasters master chooses depends on the arcane school of the student.
Abjuration: lesser dispel magic, shield
Conjuration: cold feet, mage armor, summon monster I
Divination: foes's measure, identify, true strike
Enchantment: aggravate animal, charm person, sleep
Evocation: burning hands, magic missile, magnetize
Illusion: disguise self, shadow hands, ventriloquism
Necromancy: animate skeleton, cause fear, ray of enfeeblement
Transmutation: arm to pick, enlarge person, feather fall
Universalist: One of (floating disk, identify, ventriloquism), one of (magic missle, burning hands, sleep), one of (mage armor, shield, obscuring mist)
Air: bird's eye view, feather fall, shocking grasp
Earth: fool's gold, grease, stone fist
Fire: burning hands, dancing lantern, hypnotism
Metal: gravity bow, magic weapon
Water: cold feet, hydraulic push, touch of the sea
Wood: animate rope, charm person
If you are not trained by a master you may pick all your own spells but they are limited to the Pathfinder Roleplaying Game Core Rulebook.