accept: to receive; to answer positively
except: not including; everything but 

anxious: worried/nervous
eager: excited/looking forward to

affect: to pretend; to influence
effect: a result

assure: to make certain (such as with a person)
ensure: to make sure (such as with a thing)
insure: to provide or obtain insurance 

beside: at the side of
besides: in addition to

between: two items that are related
among: three or more things related

choice: a decision or an option
choose: to make a decision
chose: past tense of choose

compliment: to praise
complement: something that completes

farther: literal or physical distance
further: to a greater extent

fewer: comparative with plural items
less: items that are singular

imply: to suggest
infer: to deduce

its: possessive form of it
it's: contraction for it is or it has

lay: to place, which is always followed by an object
lie: to recline
**For present tense only. Tip: If you can replace the word in question with put, then use lay. 

nauseated: not feeling well
nauseous: disgust

via abcarticledirectory