There are several things often overlooked.

If you disagree, attack the argument, not the poster. Ad hominem attacks make you look bad. Argue facts, don't call the other poster stoopid.

Caps is yelling. More than 1 exclamation pt and underlining for emphasis is annoying. Bolding is less annoying. Excessive use of "leet" language makes you look silly - if you can't type in "real" english, give the rest of us a break. However, don't make fun of ESL people, imagine it was you trying to type into their native language.

And stuff that makes me crazy - Cellphones - unless it's life or death, they should be off when driving, when in the checkout line, and at movies. Yes, I was the guy who actually took a cellphone out of a guy's hand and turned it off so he could hear the cashier. I was nice enuf to say "He'll call you back later" before the phone was disconected. And he called me rude - while the rest of the line cheered. Never texted, probably won't, but answer them on your time, not mine. I complain about cashiers on cells when I am checking out, if you hate your job, have the guts to quit; don't make them fire you.

Btw, I don't currently own a cell phone. Wife does tho.