If you get the spelling and stress mark positions correct, you are 95
percent of the way to a good sounding sentence.  The next thing to do is
decide on the stress mark values.  They can be roughly related to parts of
speech, and you can use the table shown below as a guide to assigning
values.

                        RECOMMENDED STRESS VALUES

                  Part of Speech         Stress Value
                  --------------         ------------
                  Exclamations               9
                  Adverbs                    7
                  Quantifiers                7
                  Nouns                      5
                  Adjectives                 5
                  Verbs                      4
                  Pronouns                   3
                  Secondary stress            1 or 2
                  Everything else             None

The above values merely suggest a range.  If you want attention directed
to a certain word, raise its value.  If you want to downplay a word, lower
it.  Sometimes even a function word can be the focus of a sentence.  It is
quite conceivable that the word to in the sentence Please deliver this to
Mr. Smith.  could receive a stress mark of 9. This would add focus to the
word, indicating that the item should be delivered to Mr. Smith in person.