Well, as for everyone has their own role-playing technique and style, it really bothers me when a user or multiple users contain both first and third person sections in their posts and it's hard to tolerate and bare with it over time. I personally prefer third person amongst anything I role-play, along with literate grammar and mass details that I perform on each setting my character takes place in. So I always allow others to realize that having both first and thirdperson is confusing and just not a right format to use and should take credit in using one or the other.
I also prefer to write lengthy, having my posts to be much longer in paragraphs than short sentences that really have not much meaning to them and you have to simply type much faster if you'd like to add on, or wait and think of a way to shorten the details a bit. I know in the game you can't type a whole lot, which I can understand any reasons why. But at the same time either on a game or on a forum, it irritates me that I have to see someone use something irreverently.
Same thing applies for your character and how you use them and attempting to change them without notice is extremely annoying and should be taken seriously as it's your creation and you should be responsible to cause less confusion. I have seen in many cases in my years of role-playing that people don't abide to rules..or that people have a character that eventually is entirely different without approval of change. Sometimes there are people that are realistic but have a sort of mary sue...or fantasy plot combined in their posts and it doesn't fit the picture.
For my best use of words, I prefer to use male/female, over boy/girl OR brute/fae. It seems more formal to say some full words, rather than short phrases in advance. Plus also using mother/father, over mom/dad or even mommy/daddy. Unless I'm a pup, than that's exceptional, since pup-hood and adulthood I sort of mix between how my character is played out and as a young generation I perform like I'm just starting to learn about things and be mentored how to speak in time.