I am a language freak, member of the grammar police, and spelling perfectionist. English is my second language, and I can't even stand it if I make an error. (Feel free to correct me when I do, because I know it happens anyway.)
Chatspeak makes my eyes bleed. Even words like 'cuz' will put me off. Endless run-on sentences, and worse, run-on paragraphs, make me want to not read anything on the Internet, ever again. The only place where capitals should be ignored is on IM.
I try to put some thought into my journal entries; I like people who do the same. I know practically everything is worth saying or even ranting about. Fandom. Life. Your new puppy. And I care, as long as it's written well.
I post pictures, sometimes. I like pretty things. I love it when other people post pictures, too. But. For heaven's sake. When you post more than one, or one that's huge? Use. A cut. The same goes for long posts, by the way. I spend too much time behind a computer and am sure to get carpal tunnel at some point in life; I do not need useless amounts of scrolling by my friendslist to take precious years off the life I have left with the comfortable use of all of my fingers.
Oh, and quiz results. Worse: quiz results with large, obnoxiously colorful graphics. I know quizzes are out there. I know how tempting they can be. But if you must disclose to the world what breed of dog you are or which Barbie you would be if Barbie was a porn star, please, for my sake - and probably the sake of everyone else on your flist - cut, cut, cut.
I have been known to take people off my friends list over the things I mentioned above. If you friend me and I don't friend you back, it's very likely for the same reasons.
I won't comment on every single one of your entries, but when you're on my friends list, I promise I'm listening. I can update five times a day or not at all. I get bored when I'm extremely busy.
Don't feel bad if I take you off my list or simply don't add you at all. It's not you, it's me. I'm sure there are plenty of people on livejournal much nicer and more interesting than me, who would love to have you on their list.
If knowing all this, you still want to be on my friends list, leave me a note. Come in, and make yourself comfortable. I'm so very happy to have you here.