[Legolas]

While monks won't be the easiest characters to play the official campaign with, it's certainly very possible.

With monk characters, it's all about attacks per round. You won't have an easy time hitting most things, but you'll get to take a lot of swings. Always keep the Flurry of Blows feat active. You also will be wanting items granting Haste for their extra attack per round. However, you may not enjoy the Circle Kick feat, even if it does give you a bonus attack.

When you hit with your fist, your damage is only somewhat better than that of most weapons, in later levels. Fists also do not have the advantage of being able to carry an enchantment; however, you can get around that by equipping gauntlets instead of bracers. In that case, sonic damage is your friend. Larger races do better at fighting bare-handed.
The alternative to fists are the kamas. You can dual-wield the kama, which means you can get up to two more attacks each round if you take the proper feats for it. They can carry an enchantment, and keep your bracer slot free. You'll need a Dexterity score of 15 to make the most of the two-weapon fighting (though equipping the right bracers before levelling up also helps).
Apart from Flurry of Blows, you'll want to make use of the Improved Knockdown and Stunning Fist abilities whenever you get a good oppertunity. The reasoning with monks is that even if you only hit on a 20 (and no matter how bad it gets, that's always enough), if you've 10 attacks per round that's still a punch every 2 rounds. And if you need less than a 20, you can dish out a serious beating.

As for other equipment, you can wear no clothing that gives an armor AC bonus or you lose most of your perks. You can use no shield or lose them, and you can use no weapon other than fist or kama or lose your bonus attacks. That's not to say that sometimes, you may not be better off in heavy armor, carrying a shield and wielding a longsword, (if you have the proper feats for that), but those times will be rare.

Apart from maximizing your attacks per round, trying to deal elemental damage and getting good saving throws, you have your armor class and hitpoints to worry about. Being hard to hit means you'll live longer, means you'll get more attacks in. Monk hitpoints aren't poor, but they're not great either. You can use CON bonusses to increase your hitpoint total, and regeneration items to help recover lost points.
You can use DEX and WIS bonusses, as well as item AC increases, to raise your AC total. Monks can get armor classes well beyond what most fighters achieve.

At its core, there are three types of monk and these are reflected in their ability scores. The Strength monk (goes well with ranger or fighter levels) has a decent chance of hitting an enemy and deals more damage, the Dexterity monk (goes well with rogue and shadow dancer levels) has a decent chance of hitting an enemy and has a better armor class, and the Wisdom monk (works brilliantly with cleric levels) has a better armor class and monk special abilities.
Constitution is useful but you'd be specialising in a skill you don't excell at, so barbarians and the like will always beat you at that game. Charisma is not much of a requirement, and neither is Intelligence.

A high intelligence will let you pick more skillpoints though. You'll want the Heal, Discipline and Tumble skills first and foremost, though Discipline is mostly useful outside the official campaign, and Tumble is an expansion skill. Heal is nice because it lets you use healing kits to best effect, and healing kits beat most (not all) healing potions in terms of value for money. Persuade is a useful one for the OC, as Lore may prove. Other skills are not all that important to monks, in most cases (but a Shadowdancer monk will benefit greatly from hide and move silently; it's a requirement in fact).

Just completing the OC, don't expect to reach levels as high as 20. Unfortunately, the level 20 monk has some big advantages over the level 19 and under monks. Fortunately, the OC is full of items granting immunities to just about anything, so it's not hard to compensate.