I'll "ditto" [@Pair of Hearts] about [@Jig]'s post.
However, I'll go into more specific details of that I can think.

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[*][b]How do I do a proper collaboration post?[/b]
I, personally, use MeetingWords/PiratePad/PublicPad. I can't seem to get GoogleDocs to do what I want and to look the way I want it to. But there are plenty of resources out there. Try out other people's suggestions and do your own research. Experiment and develop your own opinion. ^^
[*][b]How do I portray ships, buildings, and inanimate objects in general through writing without sounding boring?
What does your character notice about them? Does your character notice them at all? Are they important to the plot?[/b]
Your character comes up to a fence. That portion of the fence is what your character notices, but the fence goes on for miles. It's not necessarily important that the fence goes on for miles if the character is just going to climb it. However, it does become important when they try to find a way around it. On the other side, your character decides to jump it, making the length irrelevant. However another character doesn't want to climb it and wants to go around. Now the length is relevant. But should you mention it in your post anyway should that occur? Do you know it's going to occur regardless? Maybe, to keep your post about your character, mention such details in the OOC. But then you get into "trying to control the minutia of mundane objects," which can get excessive.
So, if your character does care about the length now, your question to ask is "will they care about it later?" If not, then don't determine such a trivial aspect. If you're the GM and you want to make sure it is that length due to other characters interacting with, then post it ICly.
I guess what I'm trying to say is "keep it in the perspective of your character." If we're talking about humans, we don't notice every little thing about something. So going into detail the colors of the banner flag on the bow of the ship would be what your character does or does not notice. Consider this when going into detail about something. 

In terms of "how should I write it?," use words that are relatively common but invoke some kind of feeling that you want to portray.
Instead of using "red," you could write "cherry-stained, angry, rosacea-like." Uniquely hyphenated words can invoke images in the reader's mind more easily than something they have never seen or read before (conflagrant).
Also, you could try to describe something that doesn't share a property with it. So, instead of calling a color by the color, describe it with an object (cherry-stained), an emotion (angry), or a physical condition (rosacea-like). Take your character's development, personality, knowledge into account when you are looking for a "more interesting" description.
Now, I don't mean that this should be done with every detail ever. That would be clunky and overbearing on the reader. So pick the traits that you want to have leave a lasting impression on the reader. 
[*][b]What is the right amount of detail in most posts? Are there any exceptions?
To go with the above, as much detail as your character notices. However, I tend to follow grammatical structures when describing something. You can certainly spend an entire paragraph on describing an object. But that should only be 3-5 sentences (more isn't really a huge problem, but I don't like going longer because then it's just taxing to read). Then, sentences are a single item/thought. Sentences can be made to go on forever, but it's important to keep your reader in mind. [/b]
[*][b]I intend to head to an Advanced role-play at some point, but I would like to increase my skill beforehand. Do you have any general writing tips?[/b]
There are two grammatical items I notice many RPers do that make it difficult (if not just irritating) to read/comprehend.
Keep an eye on the use of commas.
It tends to be generally unknown by most people when to use a comma. To remedy this, I think research would be most beneficial. Prepositional and Adverb phrases tend to be the main issue with the misuse (non-use) of commas. If you don't know what those are, then you're probably not using most of your commas right. xP

End your sentences.
Periods (fullstops) are your friend. End your thought before going into another. Most people can't comprehend multiple thoughts in one sentence. When we see a period, we know we're going to the next thought. When we don't see one, we try to keep for a few words and then just give up. 
Furthermore, sometimes a shorter, precise sentence can help invoke the finality/importance/abruptness that you want to invoke (I'm using that word a lot). 

But I'll take an example in something you've written. This isn't a "hey, look! You're a bad writer and you've already did something wrong!" We all use improper grammar when speaking, and this is a discussion thread, so it's effectively speaking through text.
[quote]It's been a while since I've been in any role-play, and while I would like to join one, I do think I could use some advice before I try and get involved again.[/quote]
[quote]It's been a while since I've been in any role-play[color=ed1c24][b]. A[/b][/color]nd while I would like to join one, I do think I could use some advice before I try and get involved again.[/quote]

This isn't the only edit this passage could have, but it addresses the idea of using periods more frequently than most do. 
It's something to consider. It's not something you need to do or people will look down on you. There will be instances when you want to drag out a sentence to invoke the feeling of "never-ending" or "shut up, already!" 

Taking this into account with the above suggestions about detail/description can make your work provoke something in others just by the spot in which you decide to place a period, the type of adjective you decide to use, etc.
[*][b]What early signs are there that a role-play will have longevity and not die out quickly? How can I help keep a role-play alive and fun as a poster?[/b] :'((((((((((((((((((
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