Omg at least pretend to make a worthwhile post.For example extending omg to oh my (or indeed 'mah') god, this gives the apearance of a longer post when really you arent saying anything extra.
Also the use of captial letters (at the beginning of a sentance) and full stops, can give the appearance of better grammar even when you still make the same spelling mistakes.
More over you can make up a whole load of bullshit thats basically saying "learn not to spam" and make it seem like your actually saying something.