Worgen are one of the hardest 'races' to get right in roleplay, you're either good at them, somewhat good at them but do some stuff wrongly, or just cringeworthy and hated by all.
But don't worry, I'm here to go over some stuff about worgen I feel people tend to gloss over, forget or just do wrong.
Two Forms
As a worgen, your character had two different forms. Their worgen, and human form, if you roleplay a feral or worgen death knight, you don't have these two forms. Now, I see a lot of worgen roleplayers staying their worgen form almost 24/7, which there's nothing wrong with but remember that not even Genn appears in his worgen form every time he's on screen, usually he's in it when in combat or entering combat, and if you're confused on when your worgen character should enter worgen form, I generally roleplay it as a last resort to get out of trouble.
Now, the transformation itself is something I see done wrong many times. The first thing you need to realize is that, your body is literally twisting, contorting and growing in a matter of seconds or minutes. That would be pretty painful, and another thing you need to realise, your clothes don't grow with you. So when Genn transforms into his worgen form he loses almost all pieces of clothing except his pants. So you can't just shift in full plate, because the likelihood is that you'll just burst because plate won't grow with your or rip away. But worgen transformations aren't as quick as Blizzard would show it to be, they'd likely take half a minute to a minute at least. Though don't use this as an excuse to suddenly appear naked in worgen form when transforming, retain at least some level of decency please.
Ritual of Balance
The Ritual of Balance is the ritual all sane worgen have gone through, and it involves eating Moonleaf to assist the mind in preparing for the ritual, and drinking water from the moon wells that recalls traumatic and peaceful events in your character's past. And they would be forced to come to terms with past guilt and regret so they may gain balance of one's self, and allowing them to shift into their human form once again after beast and human have been brought together in balance.
Undead
There are very few undead worgen around, and the only undead worgen around are Death Knights, as only the Lich King had the power to bring them back into undeath. Worgen are -very- difficult to raise into undeath due to the curse's connection to Goldrinn and Elune. But worgen Death Knights have supposed 'flaw', they cannot shift into human form and are likely more feral than their living, Gilnean counterparts due to originally being one of Arugal's worgen that escaped from Arugal, somehow and killed by the Scourge.
Appearance
Worgen appearance is clearly influenced by werewolves, from being a half man, half wolf crossbreed. But they have a few rules in their appearance. I've seen some worgen disgracefully give themself a tail, worgen have never had tails and will never have tails it's just something they don't have. And worgen fur colour ranges from blacks, to greys, to brown to shades of ginger and even white. Their eye colours consist of mostly reds, oranges, blues and greens. Worgen are also naturally muscular and retain a natural hunch, their teeth are naturally sharp and their bodies are built to run long distances very quickly, and on all fours. Worgen can also grow a form of 'beard', which grows from their chin.
Senses
Worgen senses are superior to regular senses in every way, they're able to smell animals from long distances, smell lingering scents in the air, and most importantly be able to smell blood. Their sight is incredibly clear, and worgen who once wore glasses would no longer need to in human or worgen form. Their hearing is perceptive, able to hear whispered conversations, footsteps, breathing and most likely heartbeats if they tried hard enough.
Recommended Things to Read
First of all, you should read Curse of the Worgen. It goes over many of the things in this guide, senses, history and how long it takes from the initial bite to become a worgen.
Secondly, you should read any wow-related wiki, be it WoWWiki or Wowpedia.
And thirdly, if you're able, just go through the worgen starting zone and read the quest text.
I likely missed a lot of things in this guide, but this is mostly just the basics you need to start roleplaying. Please make me aware of any errors, grammatical or lore-related as nobody's perfect. And ask any questions, as I'll try to get back to you as quickly as possible. I'll probably make an updated guide in the future, who knows.
