Be sure that you first understand the basics.  Then study these pointers.

• Do not let words between the subject and the verb throw you off.  For example, in "A study of the effects of hurricanes on coastal cities is being undertaken," the subject is study, which requires the singular verb is.  The plural nouns (effects, hurricanes, cities) do not influence the verb.  They are not subjects but objects of the prepositions:  of, of, and in respectively.
  
  
• However, be very careful when the subject is a word that denotes a portion of something – i.e., a fraction, a percentage, or a word uch as some, most, all, or none.  Here we need to ask:  A portion of what?  Thus, what is in the prepositional phrase ("of ____") will affect the verb.  Two-thirds, 66%, or most of IT is (singular), but two-thirds, 66%, or most of THEM are (plural).  Therefore, none of my work IS (singular) complete, because none of my papers HAVE (plural) been written.  Half of the pie HAS (singular) been eaten, but most of the cookies HAVE (plural) not.
  
  
• When the simple subject is "one," do not be misled into using a plural verb.  Correct:  One out of ten students does not know this rule.  Although "one out of ten" means one-tenth or 10%, the subject is still "one" and requires the singular verb does.  On the other hand, we use the plural verb when we write, "One-tenth of the students do not know this rule" and "Ten percent of the students do not know this rule" because the subject isn't "one" but a portion of something (one-tenth / ten percent), as described in the second bullet.  This is tricky – so watch out!
  
  
• With correlatives (subjects that use either . . . or and neither . . . nor), the verb must agree with the second noun (the one nearer the verb).  Thus, "Neither the professor nor the students want (plural) . . . ." but "Neither the students nor the professor wants (singular) . . . ."
  
  
• Watch out for subjects with Latin or Greek endings (not the usual English ending) in the plural form, such as data, media, phenomena, and criteria.  These words take plural verbs:  the data show, the media are, several phonomena appear, two criteria are.  (The singular forms of these nouns are, respectively, datum [hardly ever used in the singular], medium, phenomenon, and criterion.)
  
  
• Some words may look plural in form (end in s) but are singular in sense.  Use a singular verb in these instances.  Examples:  The news is not good.  Physics is a a challenging subject.  This can be tricky.  For instance, statistics is a singular noun when it refers to the field of statistics but a plural noun when it refers to a bunch of numbers:  Statistics involves (singular) the study of numerical relationships.  Statistics show (plural) that the Democrats may win the next election.