I am currently proofreading something written by a friend on Twitter, and I have come up with a few writing tips for him and will now share them with you.
The first thing you should do is to at least mouth the words you have written to make sure that they flow when or if what you have written is read aloud. You do not have to use your vocal cords, but sometimes the best way to find flaws is to move your lips and feel how the words flow.
You should expand all abbreviations and contractions. When writing in long form like this Tumblr post, you have the room to fully express your thoughts. This includes leet or net speak. I can not take anyone seriously when I have to look up the abbreviations used. Also, the more expansive you are, the easier it is for translation software to translate what you have written. Even the most common abbreviations could be mistranslated.
To add emphasis to a word or phrase, you need to use italics not all caps.
Be sure to check that your nouns and verbs match. Do not use a plural noun with a singular verb and vice versa.
You just need to make sure you are being clear and preview often before posting.