Personally, I find pickups to be an incredibly fantastic tool to achieve plausible melodies (or melody-alike "structures").
An easy way to start would be to just have a one chord pattern playing, then look for a nice target note. Let's say you go for a min7 chord and your target note would be the 5th (a G over a Cmin7, for instance). Play that note on beat one. Then start approaching it. Could be as easy as just adding the next scale tone before. So, over that Cmin7, you might want to play an F on beat 4 of the previous bar and then your G on beat 1.
Record these simple examples and compare. Listen to how much more of a "plausible structure" it'll become by just these baby steps.
Ways to expand this approach:
- Use more than one note as a pickup (in fact, it could be any number of notes).
- Now approach your target note from above.
- Now mix approaching it from below/above. This will very likely already sound like a call and response thing, which is always great to add some structure.
- Try syncopating individual notes within all of the above.
- Then add articulations. Bend, slide, hammer on, pull off, pinch, whatever floats your boat.
Seriously, you can take this very, very far.
It's too late for today, but I could record some bits to illustrate tomorrow, in case you're interested.
Fwiw, always remember: Rhythm trumps note choices! Some of the most iconic melodies are remembered because of their rhythms. Beethoven's 5th anyone?
In Scott Henderson's pretty incredible video about melodic phrasing (or so), he demonstrates that with "Jingle Bells". He's playing almost completely random notes but is keeping the rhythm intact and you will instantly recognize "Jingle Bells" (tried to find it on YT, no chance, too bad).
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