Don't forget that prepositions always take the objective case. Don't say "Between you and I"? say "Between you and me"

Two prepositions should not govern one objective unless there is an immediate connection between them. "He was refused admission to and forcibly ejected from the school" should be "He was refused admission to the school and forcibly ejected from it."

SUMMON—SUMMONS

Don't say "I shall summons him," but "I shall summon him." Summon is a verb, summons, a noun. It is correct to say "I shall get a summons for him," not a summon.

UNDENIABLE—UNEXCEPTIONABLE

"My brother has an undeniable character" is wrong if I wish to convey the idea that he has a good character. The expression should be in that case "My brother has an unexceptionable character." An undeniable character is a character that cannot be denied, whether bad or good. An unexceptionable character is one to which no one can take exception.