This post is a variety of things that have become pet-peeves for online GM's over the years, things that are best avoided or at least approached with caution.
TOP FIVE RULES OF APPLICATIONS:
1. Spelling, spelling, SPELLING! Skip the l337 speak, avoid typing parodies of accents, watch what you type. No-one's going to freak about the occasional misspelled or misused word, but constant and basic misspellings and the liberal addition of smilies or net-speak (like 'lol') in a characters description or background is a fundamental no-no. It generally gives the impression that no effort will be made on the character after they're approved. Good spelling CAN make the difference between getting approved to play a powerful character versus the cabin boy.
2. Consistency. Keep the tense and voice of the background the same. I.E. If you're writing a background in the third-person past-tense, make sure you stick to it. Swapping tenses confuses the staff-member and delays the process. When it comes to character descriptions, avoid the use of phrases like 'standing before you' or 'see's you looking and smiles'.. it's generally advisable to use the word 'you' at all, as it has a tendency to offend other players. A good description will include the basics of sex, skintone, height, eye-color, hair-color, build, clothing and approximate age. It's encouraged to include descriptive phrases like 'worn black shirt' and the suchlike to help give an impression of the characters personality and resources.
3. Balance. Unless you're playing an anime game where every character is a teenage super-soldier, it's generally unadvisable to write up one. This is where looking at the game you're applying to in detail comes in handy. Talk to staff if you're uncertain, they can generally give you an idea as to whether or not particular character types will fit into a game, and warn you if something isn't being considered right now. On places with coded character generation you're pretty safe, balance will be built in to the code for the main part. On places that use an email or @mail (the gamer's internal mail system) application system you're generally expected to be able to judge what's reasonable and what's not for yourself.
4. Politeness. Seriously. A clueless guest who asks intelligent questions and respects the fact that the game belongs to the staff is already leagues ahead of someone who is determined that everything must go their way.
5. Avoid cliches and bad chartypes. River Tam from Serenity might make a freaking awesome movie character.. but for a MU* character she blows. A good character should be able to interact understandably in a general social situation. Willow from Buffy would be an example of a good MU* character, she can interact with a wide variety of characters, has valuable skills (research, computer, and magic in later seasons), and yet is not the all-powerful character (except for that one part where.. yeh). Some examples of characters to be approached with caution would be: Poor little rich girls (or boys), teens who are masters in their fields (doubly so for teens who are superiorly talented at everything), shy characters, sociopaths, deaf or blind characters, foreign characters who don't speak the local language. The less social your character is, the harder it is to get roleplay. This is also usually true of playing evil characters.
