Here you have just a little advice before starting our exams.

#1: Loose for lose
No: I always loose the product key.
Yes: I always lose the product key.

#2: It’s for its (or god forbid, its’)
No: Download the HTA, along with it’s readme file.
Yes: Download the HTA, along with its readme file.
No: The laptop is overheating and its making that funny noise again.
Yes: The laptop is overheating and it’s making that funny noise again.

#3: They’re for their for there
No: The managers are in they’re weekly planning meeting.
Yes: The managers are in their weekly planning meeting.
No: The techs have to check there cell phones at the door, and their not happy about it.
Yes: The techs have to check their cell phones at the door, and they’re not happy about it.

#4: i.e. for e.g.
No: Use an anti-spyware program (i.e., Ad-Aware).
Yes: Use an anti-spyware program (e.g., Ad-Aware).
Note: The term i.e. means "that is"; e.g. means "for example." And a comma follows both of them.

#5: Effect for affect
No: The outage shouldn’t effect any users during work hours.
Yes: The outage shouldn’t affect any users during work hours.
Yes: The outage shouldn’t have any effect on users.
Yes: We will effect several changes during the downtime.
Note: Impact is not a verb. Purists, at least, beg you to use affect instead:
No: The outage shouldn’t impact any users during work hours.
Yes: The outage shouldn’t affect any users during work hours.
Yes: The outage should have no impact on users during work hours.

#6: You’re for your
No: Remember to defrag you’re machine on a regular basis.
Yes: Remember to defrag your machine on a regular basis.
No: Your right about the changes.
Yes: You’re right about the changes.

#7: Different than for different from
No: This setup is different than the one at the main office.
Yes: This setup is different from the one at the main office.
Yes: This setup is better than the one at the main office.

#8 Lay for lie
No: I got dizzy and had to lay down.
Yes: I got dizzy and had to lie down.
Yes: Just lay those books over there.

#9: Then for than
No: The accounting department had more problems then we did.
Yes: The accounting department had more problems than we did.
Note: Here’s a sub-peeve. When a sentence construction begins with If, you don’t need a then. Then is implicit, so it’s superfluous and wordy:
No: If you can’t get Windows to boot, then you’ll need to call Ted.
Yes: If you can’t get Windows to boot, you’ll need to call Ted.

#10: Could of, would of for could have, would have
No: I could of installed that app by mistake.
Yes: I could have installed that app by mistake.
No: I would of sent you a meeting notice, but you were out of town.
Yes: I would have sent you a meeting notice, but you were out of town.

Vía: Techrepublic vía Reddit