• about
• above
• according to
• across
• after*
• against
• along
• along with
• among
• apart from
• around
• as*
• as for
• at
• because of
• before*
• behind
• below
• beneath

• beside
• between
• beyond
• but* (except)
• by
• by means of
• concerning
• despite
• down
• during
• except
• except for
• excepting
• for
• from
• in
• in addition to
• in back of
• in case of

• in front of
• in place of
• inside
• in spite of
• instead of
• into
• like
• near
• next
• next to
• of
• off
• on
• onto
• on top of
• out
• out of
• outside
• over
• past

• regarding
• round
• since*
• through
• throughout
• till
• to
• toward
• under
• underneath
• unlike
• until*
• up
• upon
• up to
• with
• within
• without

• for*
• and 
• nor
• but *
• or
• yet
• so
• (then)

• By far the most common fanboys are and, but, and so. You can pretty much forget the rest.
• "For" is only a fanboy when it's used as an old-fashioned way of saying "because". That's less than 1% of the time. More than 99% of the time, "for" is a preposition.
• "But" is almost always a fanboy. Very rarely, you might see it used as a preposition. The word "but" is only a preposition when it's used with the meaning of "except".
• "Then" is not a true fanboy, but you can think of it as an "honorary fanboy".
• "Nor" doesn't follow the usual rules. Try hard to forget that it exists.

• after*
• although
• as*
• as far as
• as though
• because
• before*
• even if
• even though

• if
• inasmuch as
• in case (that)
• in order (that)
• insofar as
• in that
• lest
• no matter how
• now that
• once

• only if
• provided (that)
• since*
• supposing that
• than****
• though

• till
• unless
• until*
• when
• whenever
• where**
• wherever
• whereas
• whether or not
• while

* Words marked with a single asterisk can also function as prepositions.

** The word “where” is more commonly used to introduce an adjective clause or a noun clause.

*** These pairs express “degree” and do not follow the usual pattern.

**** The conjunction “than” is unusual in that the predicate of the subordinate clause is often omitted.