Or at least look like you do?
If you're anything like me, you don't care about gear or stats. You hear someone talking about their dps number or their health total and you're like "Is that impressive? I really don't know. Please tell me."
If you're like me, you just want to be told what to do. No muss, no fuss, just "Wear this, hit these keys, and don't stand in fire."
And you do it and the administration pats you on the head for being a good little follower.
Trouble is, not everyone has someone willing to sit down and take you through what you should do. If your guild has class leads, that's usually their job, but more often than not you need someone you feel comfortable with.
So let's see what I can whip up.
There are many many cookie-cutter talent specs out there, and if you're like me you want to just grab one and go. Good resources are Wowwiki for your cookiest of the cookie cutters, but if you want more in-depth options, I suggest the Build Shop posts on WoW Insider. It gives you more info than average without being 71 billion miles long.
Even if you have a GORGEOUS spec, it's useless if you don't know how to use it. You need to be aware of what spells and abilities to use when, or you're just going to be sitting there as (for example) Arcane wondering why your Fireballs don't do more damage.
Once you have an idea of which spec you want, try heading to the Class Mechanics forums at Elitist Jerks. Click on your class, then browse the topic titles for the spec you're interested in (you may have to poke around a bit; just try to get comfortable with how things are set up). They'll give you more in-depth spec details as well as a rotation, and if you can't find a rotation it's probably in another post. Keep looking.
Sometimes it's listed as "priority" abilities, sometimes it's a fancy image, but there are rotations available.
I've stopped trying to map out the perfect gear wishlist for my character and have gone to Lazy But Effective town, where I pay attention to what STATS I need, and how much of something is too much (like hit -- you can have too much hit), and then the item level of the gear I have versus the gear that drops (item level needs to be turned on in your Interface for it to show on gear).
And if the gear that drops is full of the stats I need (as opposed to wasted stats that are useless for me) and has a higher item level than what is currently on my person, I roll. If it doesn't meet either of those criteria, I don't.
You can find descriptions of what stats your class should look for on the Wowwiki Class pages (click on your class and search for a section labeled "Weapons/Gear/Armor" or "Stats").
Even if you get the latest spec and gear and rotation, it's all likely to become outdated. If you start to hear whispers about your class getting buffed or nerfed, you'll want to reevaluate these things at that time.
No matter who is telling you what to do, or how smart they are, someone else will always think another way is better. In the end, if you try something and don't like it, try something else.
Also, if there's someone in your guild who has your class but better performance, ask what class resources they use and get them to link you to their favorite post. This way, they don't have to sit down and spoon feed you, but you don't have to wade through hours of searching.
If you know what to look for, you don't have to read all the theorycrafting to be competent. You just have to know what the theorycrafters suggest based on the latest game changes and then be flexible on your character with what's current.
It doesn't have to be rocket science or include hours of research -- in fact, the most effort involves getting comfortable with the resources available and pro at skimming to the sections you need.
And you'll be fine.