Some problem pairs

Advice (guidance) e.g. I have a feeling they don’t follow their parents’ advice. noun
Advise (to recommend) e.g I advise you to see a dentist. verb

Effect (result) e.g. One of the effects of the oil spill is the ecological disaster it brings about. noun
Affect (to have an impact) e.g. The new taxes will affect those on high incomes. verb

Borrow (to use something that belongs to somebody else) e.g. I borrowed a book from the library.
Lend (to give something to somebody that belongs to you) e.g. I’ll lend you my bicycle if you bring it back on Friday.

Lose (unable to find something) e.g. You’ll lose your things if you don’t look after them.
Loose (not tight) e.g. Those trousers look very loose on you!

Their (belonging to them) e.g. They are having their break.
There (to point something out) e.g. Look over there! Can you see her?

Quiet (silence) e.g. We need a quiet place to study.
Quite (rather) e.g. They were quite satisfied with the service at the hotel.

Whether (if) e.g. Do you know whether they want to come to dinner with us?
Weather (climate) e.g. What’s the weather like in Brazil?