In general, proofreading your description shouldn't even take that long. I prefer keeping my descriptions to two paragraphs or less, so a quick glance or two over your work should be enough. Remember, your descriptions should encourage people to interact with you, not drive them away! Proofreading your description is like brushing your teeth and fixing your hair. People are more inclined to hold a conversation with you if your breath doesn't smell like rotting corpses.
Let's use the description of Daniel Whitcomb's Night Elf Druid as an example. If he were drunk and half asleep when it was written, it would look something like this:
"This man walks with a ditermin gait and his eye glow intensely he wears the tabard of the Cenarion Circle and the signs of the Argent Dawn and the Northrend Commonwealth are pinned to his cloak he wears a ring wedding ring finger. Another ring says hes an honored protector of the Bronze Dragon and another for the Violet Eye.
His clothing varies from day to day but it usually leather with a bear or wolf about his shoulders and antlers on his head. He smells."
What a mess! Do you want to play with that? Probably not. Luckily for Daniel, a little proofreading and revision makes it much more attractive.
"This man walks with a determined gait, and his eyes glow intensely. He wears the Tabard of the Cenarion Circle, and the insignias of the Argent Dawn and the Northrend Commonwealth are pinned to his cloak. He wears an elaborate insignia ring on his wedding ring finger. Another ring marks him as an honored protector of the Bronze Dragonflight, while yet another is emblazoned with the shield of the Violet Eye.
His clothing varies from day to day, but it's usually rustic leather, with a bear or wolf pelt about his shoulders and antlers on his forehead. He smells of smoked dreamfoil."
There are a few other things you should take note of in this description. The first one we'll mention is the length. This description could be a little longer before reaching the danger zone, but there's no real reason for it. Your goal with your description is to attract people to you. It's there as fuel to kickstart some RP. You want the description long enough to give someone a hook and an idea of what they're getting into, but short enough that they'll actually finish reading before they get bored. Writing a novel as your description will just drive people away, even if you think it is amazingly well written. They'll have lost interest in you before even speaking to you. That is definitely not what you want, considering roleplay is such a highly social activity.
Next, you'll notice he has a little blurb about body language. How you carry yourself in real life often determines someone's first impression of you, it suggests what kind of person you are. It's the same in these descriptions. Is your character an angry one? Shy? Nervous? Energetic?
Another thing you'll notice about Daniel's description is he drops a number of specific items in there. He has a few neutral items such as the animal pelts, and he also has some more specific things such as his rings. These hooks will probably be what inspires others to talk to you. Alongside that description of how voluptuous your female draenei mage is, you may want to describe a few pieces of jewelry. "Nice earrings" is a much easier conversation starter than "Nice boobs."
Appealing to senses other than sight is a good idea, too. Daniel's Druid smells like Dreamfoil. Maybe your character likes the smell of Dreamfoil. Maybe your character hates the smell of Dreamfoil. Maybe you want to know what makes him smell so bad. This one little hook opens up a wide variety of ways his character can be approached.
Sound is another good thing to touch on. The sound of your character's voice is good one, because it's something you definitely cannot get just out of text-based dialogue, but could inspire conversation. It can be a little harder to describe the sound of a voice than it is to point out jewelry, but it's good inspiration for conversation if done well.
You do not always need to get as specific as Daniel does with his jewelry and items of note, but it can help. Characters who have an interest in Karazhan, Dalaran, et cetera will pick up on his ring from the Violet Eye. Maybe they'll ask about his ring from the Bronze Dragonflight. These are items acquired in-game, there's no shame in displaying them on your character. Lording PvE accomplishments over people is a bad thing, but integrating them into your roleplay experience is good. Just remember to do it in a way that is accepting of others. PvE accomplishments can be good RP inspiration, there's not always a need to disconnect the two.
I think that's about all we can milk out of Daniel's Druid for the moment, so let's talk lore. Azeroth is a very rich world with many possibilities. Backstories can be extremely diverse, but common courtesy is to keep your character within the limits of Warcraft. Work with what we know. If you want to roleplay in Stormwind, make sure your character is one that would actually be allowed in Stormwind.
Example: "Jane walks with grace, long white hair flowing down to the small of her back. Her robes are just slightly too long for her frame, trailing behind her as she moves. A dark green brooch can be seen about her neck, a demonic rune set within the stone.
On her back are twelve pitch black wings, each of them flexing and relaxing independently of one another, as if they have a mind of their own. Horns of flame sprout forth from her forehead. She growls ferally at all who come near."
Not the best description I've ever written, but I think you see what I mean. Roleplay requires a certain level of suspension of disbelief, but a little realism is required to keep everyone's experience a good one. That person would never be allowed in Stormwind, or any other city. This character probably shouldn't even exist in the context of Azeroth.
If you have a lot of Warcraft knowledge, you can beef up your descriptions without it being ridiculously out of context. If you're a beginner, keep it simple! There's no harm in that.
"Timmy looks like your typical Westfall farmhand. His hair is unkempt and there is a bit of dirt on his clothes. His hand grips the pommel of the simple sword at his hip tightly, his knuckles white."
That's a pretty simple, safe description. If you don't know much about Warcraft yet, it works! A simple character from a simple zone, with the hook of him and his sword. It might signify he's a very nervous man, or a very aggressive person trying to hold himself back. This will raise questions, which is a good thing! As you learn more about Warcraft and explore more of the world, you can flesh this out. You can personalize him, make him something more.
Immersion is a massive part of roleplay. Craft your character as they would be in the world you are playing in. It's a rich world, use it!
Remember, these are guidelines and not rules. There is no set length that is the 'best,' some just work better than others. You don't need to include all of the things mentioned, there is no level of detail required. I believe these suggestions will lead to a better experience, but the quality of your experience is ultimately determined by you and not me.
Oh, and by the way, if you want to avoid the creephats out there... don't describe your character's boobs and their awesomeness. Trust me.