Not commonly seen even from unpublished writers, who are probably familiar with the difference because they're all waiting for an acceptance!
"We accept your invitation to your party, except for Bill, who will be away on that day."
ADAPT, ADEPT, ADOPT
Adapt means to adjust, adept means skilled and adopt means to take as your own:
"Some people cannot adapt to new surroundings."
"He is very adept at dodging awkward questions."
"He tends to adopt the attitudes of those around him."
Adverse means inauspicious, hostile; averse means disinclined, repelled.
"I'm very much averse to making a long, arduous journey under such adverse weather conditions."
Advice is the noun and advise the verb.
"His advice was that we should advise everybody to either stay away or be extremely careful."
Affect is a verb; effect is a noun.
"Bad weather will affect the quality of the fruit."
"The effect of bad weather is a reduction in fruit quality."
ALREADY, ALL READY
Already means by this time; all ready means prepared.
"Are you already packed?"
"Yes, I'm all ready to leave."
ALTOGETHER, ALL TOGETHER
Altogether means wholly; all together means everybody in a group:
"It's altogether too bad you can't come."
"All together, now: 'Good morning, Sir!'"
ALL RIGHT, ALRIGHT
All right is the correct form; alright is grammatically incorrect.
Allude means to refer to; elude means to dodge or escape.
Allusion is an indirect reference or hint; illusion means deception or mirage.
ALL WAYS, ALWAYS
All ways means by every way or method; always means all the time, forever.
Annual means yearly; annul means to make void or invalid.
ANYONE, ANY ONE
This is quite tricky. Anyone means anybody, any person at all; any one means any one person and is followed by "of".
"Does anyone else want to come?"
"Any one of you is welcome to come along."
Appraise is to assess or estimate. Apprise is to inform or notify:
"I will appraise the situation and immediately apprise everybody of my conclusions."
Please don't make your character say or write anything like this, though--unless you want him to sound like a pompous twit!
Ascent is an upward movement; assent means agreement.
Assistance means help or aid; assistants is the plural of assistant, one who gives help.
ASSURE, ENSURE, INSURE
Assure means to guarantee; ensure means to make sure; insure means to protect against loss or damage:
"I assure you there's no call for alarm."
"To ensure your crockery doesn't get broken, wrap it all in bubble wrap."
"In case of breakage or loss, you should insure everything with a good insurance company."