As with all these “beginning a such and such” articles, I suggest going with the template, then tweaking things to fit your own preferences and personality after giving it a test run to familiarize yourself with the build’s options. Be aware of how each talent affects your overall performance, instead of taking something just because “it sounds good” — a bit of research and/or number crunching can mean a difference of hundreds of DPS!
Of the three trees, marksman is definitely getting the least specialization these days. This holds especially true in PvE and raiding, where MM is seen as the “PvP spec”. This is because it tends toward burst damage (hit them fast, hit them hard) at the cost of sustained DPS (firing at a boss for 10 minutes straight). It’s possible for raiders to work around the mana and aggro issues with careful cooldown management, though, and the spec brings along its own utility. MM hunters are highly mobile thanks to their arsenal of stings and Readiness, a quality that comes in very useful during fights heavy on choreography. The main reason I like to bring a MM in our raids is their very valuable raid-wide buff, Trueshot Aura (it stacks with Might/Battle Shout and is analogous to Abomination’s Might/Unleashed Fury). Most other builds use the MM tree to complement their specs for a reason, so let’s take a look at a good raiding spec for MM. (The following is taken almost directly from Wowwiki.)
Itemize for agility > attack power > crit to get the most out of those talents.
* Major Glyph of Steady Shot
* Major Glyph of Improved Aspect of the Hawk
* Major Glyph of Hunter’s Mark
* Minor Glyph of Revive Pet
* Minor Glyph of Mend Pet
* Minor Glyph of Feign Death
* Major Glyph of Trueshot Aura
* Major Glyph of Arcane Shot
* Major Glyph of Aimed Shot
The suggested shot rotation is Steady Shot with Chimera Shot at every cooldown (usually a 3:1 ratio). Weave Arcane, Multi and Aimed as available, and be sure to use Kill Command on those pets. Also remember to Misdirect to the tank and drop aggro whenever a cooldown is up, to keep aggro under control. There are macros available for some of this, but I’d suggest getting used to the rhythm of handling a MM rotation before anything of that sort, especially since there can be quite a bit of variability due to the amount of movement involved in a fight.