The standard user interface actually promotes bad shooting habits for hunters. This is because the action buttons have a nice swirly movement to indicate abilities coming off of cooldown, and then a little flash once they're ready to use again. For most classes that's just fine - people can just use their abilities as soon as they are ready. But hunters have an extra problem that other classes don't have: if we just cast a new ability as soon as we can, we'll find our damage going down by quite a bit because Auto Shot will get delayed.
Auto Shot is one of our bread-and-butter damage abilities, and it goes off automatically every so often, depending on the speed of our ranged weapon. Basically, it gives us a window of time in which we can cast other abilities, such as Arcane Shot and Multi Shot, and Steady Shot. Arcane Shot and Multi Shot each cause a 1.5 second global cooldown on all our special abilities, but do not delay Auto Shot at all. Steady Shot, on the other hand, has a 1.5 second casting time which can delay Auto Shot if we cast it at the wrong time. In order to do good damage, we need a visual way to see just how much time is left before our next Auto Shot - but there is no obvious way to track this in the default UI.
To help me with this, I use an alternative casting bar called Quartz, which shows me a timer on Auto Shot and helps me to time my other abilities so that they don't disturb the flow of my damage so much. There are a number of other mods that help you keep track of your Auto Shots, however, such as ZHunterMod (which has a host of other features too). Feel free to try out various ones and see which suits you best.
For the future, I'm interested in trying out Sorren's Easy Rotations, to get a better handle on exactly when I should be casting which abilities.
Threat is another blind spot hunters often have. Without an addon such as Omen, it's very easy to just shoot away to your hearts content until you find enemies suddenly turning against you instead of the main tank. "Fine!" you say to yourself, "I'll just Feign Death! Tee hee!" But as you cry out your false death cry, you see the monster that was coming at you doesn't go back to the tank - instead he goes after the healer! Suddenly all havoc breaks loose: your tank starts running around like mad, you jump up and try to help somehow, your healer dies after all, your tank dies, everyone else dies... and now all the monsters are coming after you again - and Feign Death is still on cooldown.
In order to avoid this utterly embarrassing and unpleasant situation, you need to know when a monster is about to turn away from the tank, and Feign Death early, before any of these terrible things happen. Omen's little bars can tell you how close you are to that point of ultimate shame, not only saving you all that time and money you would have spent on wipes and repairs, but helping you to preserve your hunterly self-respect, and your confidence that you can do a good job.
Pet ability training
The last problem of the day has to do with education. In real life, we often learn how to teach a pet from books or pet training schools, but in WoW, we have to run around the world and learn important abilities from various animals in the wilderness before we can teach them to our pets. Although most of the recently added abilities are available from pet trainers in the game, the old ones are still annoyingly difficult to find in the wild.
Fizzwidget's Hunter's Helper helps a lot with this, by letting you search a database to find out the nearest place you can go in order to get the pet ability you want. You can also use it to tell you what abilities you can learn from any animal you see just by mousing over it and looking at the modified tooltip. It doesn't save you the trouble of actually trekking around and taming those various animals, but at least you can be sure where to go to find what you need.
Likewise, the actual interface mechanism for training your pet is rather awkward. You have to scroll through a list of confusing and disorganized abilities, and hope you can everything you want before you run out of training points. Addons such as Beast Training and Beast Spell rearrange all this in a more graphical chart, so that choosing your pet abilities is just like choosing your own talents. It's far easier to use, and more intuitively satisfying too.