Okay, so there are many out there who do one-liners. While at times, this is alright, but only if the person you're rping with didn't give you much to work with. Otherwise, if you keep giving one liners, and want to make your posts longer, this'll help ^^.

1. Mainly, be more descriptive, but not off topic.

Examples:
Adam woke up, then stretched slowly. He walked over to his desk, looking over the papers on there. There was a letter there that hadn't been there before.

Improved:
Sunlight wandered into the room, falling onto the young man's face. Adam's eyes opened slowly, realizing it was morning.

Sitting up, he rubbed his eyes. The brunette got up, and now began to stretch. His brown eyes wandered over to his desk.

When he was done stretching, he strolled over to the desk, looking at the scattered papers before him. One stood out. It was a letter, and Adam could swear it wasn't there before.

2. Use variations with words.

examples:
He walked over to the door.

Improved: He strolled over to the wooden door.

3. Don't speak in leet.

example:
I watched u walk over 2 me.

Improved.
I watched you, as you walked over to me.

~~~
There are probably others ways you can improve your rping skills, and others may post them. Spell checking always helps, if you don't have it on your computer, then go onto a search engine and look up "Free spell check"

There will be downloads as well as just normal sites where you can copy and paste your text, click the button, then correct all errors. Pretty simple.

If you use firefox, which you probably should since Menewsha is optimized for firefox, then there should be a feature that spell checks your posts :]

I have opera, so I have to go to a website XD.

Another tip:

4. If you are rping with more than one person, you should remember to wait for at least two of them to reply before replying, unless you are in a conversation or a place where they are not. You don't want other rpers to be left behind.

Something to add...

While being descriptive is great - and even helpful ....

If you bog down your post with the thesaurus, it will be actually less enjoyable and easy to read than spare description. Ie: More description is not necessarily better description.

Here are some posts to illustrate....

Overly-flowery description post example:
Alfalda's bright, intelligent azure irises took in the glorious brightness of early morning's golden sunlight which streamed warmly through the darkly stained wooden slats of his bedroom window's shutters. Dust motes sparkled, danced, and soared through the spears of light that slid gently into the space of which was proudly labeled "Alfalda's Room" in neat curling script his mother had painted upon the wooden door to the place in which he slept through the night's cold, silent hours. The warm heart beating regularly in his chest swelled with good-natured happiness. "Good morning," the words slipped from the pink petals that were his lips and were heard only by the dancing dust motes and the row of familiar plastic figurines that lined the metal shelves of his moss-green walls....

I don't know about you guys... but after awhile, I'd lose track of what was being said at all. Too many words. Here's what I would suggest instead....

Descriptive, but not overly-so:
Alfada opened blue eyes to the first, warm rays of morning that streamed through the dark wooden slats of his blinds. Contentedly, he watched dust motes dance through the air and he whispered, "Good morning," to the empty room. His eyes scanned the familiar rows of action figures that trooped across the metal shelves against his walls and he smiled.

http://www.mozilla.com/en-US/firefox/ :]

Yeah, overly flowy things are confusing XD. Another addition:

6. Do not point out someone elses errors in an rp. In fact, you should not comment on other's posts. If you really need to, pm them. If they give you something odd, just go with it.

Example:
((Dude, your post sucks.. That doesn't make sense at all..))

Better way to do it in a literate way:
Peter looked at the glowing floaty figure in confusion. How did this happen?

Another better thing to do Pm them:
Hey, your post needs some corrections. It doesn't really make sense how your character is suddenly floating and stuff..