_Commence_ for _Begin_. This is not actually incorrect, but--well, it
is a matter of taste.

_Commencement_ for _Termination_. A contribution to our noble tongue
by its scholastic conservators, "commencement day" being their name
for the last day of the collegiate year. It is ingeniously defended on
the ground that on that day those on whom degrees are bestowed
commence to hold them. Lovely!

_Commit Suicide_. Instead of "He committed suicide," say, He killed
himself, or, He took his life. For married we do not say "committed
matrimony." Unfortunately most of us do say, "got married," which is
almost as bad. For lack of a suitable verb we just sometimes say
committed this or that, as in the instance of bigamy, for the verb to
bigam is a blessing that is still in store for us.

_Compare with_ for _Compare to_. "He had the immodesty to compare
himself with Shakespeare." Nothing necessarily immodest in that.
Comparison with may be for observing a difference; comparison to
affirms a similarity.

_Complected_. Anticipatory past participle of the verb "to complect."
Let us wait for that.

_Conclude_ for _Decide_. "I concluded to go to town." Having concluded
a course of reasoning (implied) I decided to go to town. A decision is
supposed to be made at the conclusion of a course of reasoning, but is
not the conclusion itself. Conversely, the conclusion of a syllogism
is not a decision, but an inference.