I find that building off a strong melody line seems to be the best way to guide your writing. Once you have the melody the syllable count and accenting seems to take care of itself.
But it is important to have a few melodic options or else it becomes too linear and will not hold the interest of the ear.
Also, try to use atleast two different rhyme schemes in your songs, if its just going ABAB throughout they won't be as inclined to keep tuned into the song, because nothing new is happening.
Good luck