For the new or seasoned roleplayer, here are some tips which might help you in your day-to-day RP:
Figure out your character's motivating factors. Money and fame, converting evil characters, opening a bar, being a well known dancer? Knowing a couple of them will help you focus your RP.
Figure out what your character is good and bad at. Maybe your character can hold his liquor, but he's clumsy. Or maybe she's good at managing money, but she's stingy and critical of others' use of money. Flaws/quirks and talents will go a long way in making your character more real.
Make mistakes. Often we make small mistakes while speaking to one another, like forgetting to say not (I'm not angry at you v. I'm angry at you). Your character isn't perfect, so purposefully make typos (or at least do not correct those you make).
Imagine what you would do. Although most characters are very different from their players, some things are pretty universal. Go to a mirror and think about what would happen if you received shocking news. What happens to your eyes, your mouth? Take real life reactions and describe them in an emote.
Use your environment and take creative license. Not every aspect of a room can be completely described. On Lensmoor, we prefer rooms with 3-6 lines. So, try to keep visible items down to prevent clutter. Pretend there's a candlestick near the bed or that one bush is particularly more floral than the others.
Make use of the time and weather commands. Your character might be using mind over body, but rain and snow are still annoying.
Keep OOC and IC separate. What you know and what your character knows is very different.