Just a general reference, to make sure you've got the right word.

Its and it's were covered under the apostrophe section.

To, too and two.

To is a direction. "We are going to the show."

Too means also. "You can come, too."

Two is a number. "There were two of us going."

There, their and they're.

There is a direction. "We're heading over there."

Their refers to a possession. "Those are their newspapers."

They're is a contraction, short for "They are." "They're never around when you need them."

Lose and loose are different words.

Lose is the present tense of "lost," as in, "Don't lose your bag."

Loose is the opposite of tight, as in, "The top was very loose."

Similarly, loser is what you call someone who never wins; looser is what you'd call a jar top that's more unscrewed than the one next to it.

Then and than are also different words.

Then is an order of events: "First we got dinner, then we went to the show."

Than is a comparison. "Blink is cuter than Mush (but that's just my opinion)."

Through and thorough both have too many letters that aren't pronounced and look similar, but are also not the same.

You go through a door to the other side.

You do a thorough job if you do a complete job.

(And just for kicks, Thoreau was a famous writer in the 1800s. Personally, I can't stand him.)

Lie and lay are an case of active and passive.

I lie down. [I perform a direct action.]

I lay the cup down. [An action is performed on the cup.]

Drank and drunk are also active and passive.

I drank coffee. [I perform a direct action.]

The coffee was drunk by me. [An action is performed on the coffee.]

Whose and who's are also different; the first is belonging and the second is a contraction.

Whose cup is that?

Who's going out tonight?

Would've is a contraction and is not "would of." What you mean is actually "would have." Similarly, "could've" and "should've". The word is have, not of. So it gets an apostrophe in place of the missing letters.

Affect is a verb, and effect is a noun. Thus, a person is affected by events; those same events might have a large effect on a person. Affect is what you do; effect is what you feel. (The exception to this is that effect can be used as a verb when it's a synonym for achieve, so one can effect change. Otherwise, though, it's strictly a noun.)

Addictive is a real world, "addicting" is not. Something is highly addictive, or has addictive properties.

Impact is a noun, not a verb. Something has an impact, but a person can not be impacted—impacted is what your teeth are if the dentist needs to dig them out. Furthermore, if anyone ever uses the word "impactful," I shall slap him or her silly, because that's not actually a word at all.

Something confusing you, or did I miss something that should be here? Let me know.