Understanding that the melody line and the bass line should share some of the same notes. Here is what I do for what ever that is worth. I gather my melody notes from chord's pentatonic scale.
C major pentatonic = C, D, E, G, A The C, E and G are the chord tones and the D and A are two safe passing tones.
To dicide which notes I go to the keyboard. That C chord is being played over or under a lyric word. Which note sounds best with the lyric word?
One note per lyric word - understand Ma-ry and Lit-tle take two melody notes. The lyric will be in phrases, your melody should flow with that phrase, i.e. make melodic phrases.
For me - works best on the keyboard and I like to tie melody notes to the lyrics being used. I start with the story that leads to a verse and lyric format, that leads to the chord progression and that leads to the melody. That may not work for you - start with what ever works best for you, it's a chicken or egg thing. When you finish melody, harmony and rhythm have to flow together.
As long as the C chord and the pentatonic notes - C, D, E, G and A are harmonizing well and good, however, when the melody/lyric move over another chord then your melodic phrase should contain the notes of
that chord's pentatonic, etc., etc.
Melody is not a stream of notes, there need to be pauses - time for the melody to breath - two notes close together then a leap of at least a 3rd seem to work well - time those with your lyric flow. Those leaps and what you do after the leap seem to make the difference, IMHO.
http://www.archive.org/details/exerc...melo01goetgoog Talks about leaping.
http://www.ibreathemusic.com/forums/...p/t-15818.html Talks about wave action.
Both add interest to the melody line.
Good luck.
