Learners of English

Just some thing I want to talk about regarding "linguistic posture". Ways to avoid obviously being non-native. This could apply to job applications or just texting.
Don't overdo abbreviations. I completely understand why learners use tons of abbreviations. It lets you convey so much with such an easy to remember short burst. But there is a certain persona you put off by using so many abbreviations. It's not really positive. An occasional "lol" here and there is fine, for conveying simple ideas, but I've seen learners use exclusively words like lol, and it looks very unintelligent. The problem is that native speakers sometimes use that many acronyms, and when they do it looks very very bad. Non-natives do it because they can't speak the language, natives do it because they can't speak the language, and that bad. And people naturally assume you're a native. On top of all that, abbreviations come and go in months. Certain abbreviations will give you away (as if you need to hide, but still) as a foreigner. It's mainly "cringe-worthy", because it looks so out-of-touch. Spell out words as best you can. At this point, in 2015, no native speaker says "U" instead of you. If they do, they don't capitalize it, and it looks very very unintelligent. "w8" is also not used at all. I understand that these sort of things can be pretty cool from an outside perspective, but they look bad most of the time to natives with any respect for their language.
Another basic way to make your English look more respectable, is capitalizations. The more accurate the better. Always capitalize I (я), it looks so much better when a person capitalizes correctly. Sometimes on the internet, in order to be ironic, people will intentionally not capitalize words in order to look dumb.
Also, mixing up "your" and "you're" and mixing up "their" and "they're". Very important to get right. (Can someone explain how learners of English get that wrong? Seems easy to understand to me if you come from a language where they aren't pronounced the same, but I still see it used wrongly by non-natives)
The only punctuation problems, is getting the right apostrophe. ' is the only shape that works. "You`re" looks strange, is always noticeable. Not really that important. As long as you're USING apostrophes, you're doing well. A downward line in text. A clockwise turning swirl shape, or a diagonal (going up to the right) line when handwriting. Very very very few people know where to put commas in English. Hell, I'm not even sure at times, and I know English better than my teachers. Certain cases, commas are very important. In cases where they distinguish between "vocative" and otherwise. "I know john." VS "I know, John." . Nobody knows what a clause is, those commas don't matter anymore. =*(
There have been "studies" that show (at least in English), correct writing (even in casual texting) is "more attractive", basically, it just looks better in every way.
Just like I always write ё in Russian, because it's not my language. I'm just a visitor. It's an obligation to me to not bring down Russian, as a non-native.
Surely, mistake are fine as a learner, they happen. But there's a standard line you want to meet, since there are natives who don't speak well, and look dumb, when people see you writing like those people, they assume you're a dumb native =(, when in reality you're light years ahead of native speakers of english, who on average know .7 languages, whereas you will know 2+.