- It's "definitely", not "definately" or—even worse—"defiantly". Defiantly has a whole different meaning.
- "A lot" is two words. TWO. "A" and "lot". Not "alot". I defer to Hyperbole and a Half.
- "Would/could/should of" is not a thing. "Would/could/should have" is. Shortened it's "would've/could've/should've".
- Regardless of anything else, NEVER USE IRREGARDLESS.
- For all intents and purposes, not "for all intensive purposes".
- Adverbs ending in "-ly" are well and good, but please try not to overuse them. They can make your writing seem lazy in my opinion.
- "Pre" does not need to be followed by a hyphen most of the time. (prepurchase, prepay, etc.)
- In fact most hyphenated words probably don't need hyphens.
- Speaking of, if you use "--" in your writing switch to an actual em dash. It looks like this—the alt code for it is alt+0151. Learn it, live it, love it. Oh, and no spaces around it please.
- "It's" means "it is". "It's starting to become clear."
"Its" indicates possession. "Murky killed the tower after its ammunition ran out."
- There's a difference between "your/you're" and "there/their/they're".
"Your face makes it seem like you're (you are) getting sick."
"There is no reason to take their words at face value. They're (they are) just trying to make you mad."