How to not write bad - Ben Yagoda 2013

This should not be necessary, but ...
How to not write wrong

Do not write your (possessive of you) instead of you’re (contraction of you are) or it’s (contraction of it is) instead of its (possessive of it), or vice versa. If you do, it looks very bad and you will be mocked. Spell-check will not help you out. You just need to be mindful.