Commonly Confused Words, a Few

More problematic words may be found in Chicago Manual of Style, page 262

Affect (v. to influence, to change)                      
Effect (n. a result, a consequence)

All ready (everyone is prepared)
Already (adv. by this time, previously)

Allusion (n. indirect suggestion)
Illusion (n. false or misleading idea)

Altogether (adv. completely)
All together (at the same time or place)

Anyway (adv. in any case)
Any way (in any manner)

Decent (adj. proper, respectable)
Descent (n. action of going down)

Desert (n. hot, dry region)
Dessert (n. last course of the meal)

Emigrate (v. to leave one’s country)
Immigrate (v. to move to a new country)

Farther (adv. greater physical distance)
Further (adj. additional; to an advanced point)

Its (pronoun, possessive)
It’s (contraction for “it is”)

Precede (v. to go in front of someone)
Proceed (v. to move forward)