How to Recruit Valerie
Seemingly destined to be a paladin of Shelyn, Valerie found herself plagued by a most peculiar ailment: beauty. Unable to endure the fawning displays of numerous suitors nor continue to waste her time on vain artistic expression, she forsook the suffocating confines of aristocratic chivalry and took up the more practical profession as a warrior. That's not to say she dropped all of her noble ideals - she's a stickler for justice who is determined to bring order to the Stolen Lands and perhaps a bit too arrogant for her own good.
Perhaps one of the most straightforward companions in the game, Valerie is your tank. As a Tower Shield Specialist, all you have to do is give her a one-handed weapon of some sort, strap on the biggest slab of a shield you can find and suitably heavy armor, then let her lead the way. It's quite possible that her Armor Class will be approaching thirty when the rest of your warriors will be doing well in the low twenties, so controlling the enemies and getting them to attack Valerie will often be a key to your early success. That said, she's not the perfect warrior, as her Strength isn't as high as it could be. This will lead to a somewhat mediocre offense and a tendency to get encumbered by the heavy kit she wears into battle. Fortunately her high Constitution will stave off fatigue and exhaustion somewhat, and further cement her role as a tank by supplementing her high Armor Class with a deep pool of HP.
While wearing a tower shield will hinder her offensive capabilities, this will clear up when she gets the Tower Shield Specialist ability at the 5th level. Until then, she'll be a step behind Amiri and Jaethal, offensively, a deficiency you can remedy by swapping out her tower shield for a heavy shield, should you feel so inclined. Also, don't feel married to the bastard sword she starts with - they're in somewhat short supply in the early game, so like Amiri, be flexible, don't specialize, and give Valerie the best one-handed melee weapons you find.
Valerie gets the typical Fighter class skills: Athletics, Knowledge (World) and Persuasion. Her heavy equipment will hinder her Athletics skill to the point of not being competitive, and her Intelligence isn't all it could be, so invest in Persuasion, instead.
It's hard to imagine a party that wouldn't be better off without Valerie in it, and if you need a solid, well-defended character to draw the enemy's attention, you won't find a better companion than Valerie.