I wonder how the professional or seasoned songwriters do when he came up with a melody and tried to find a suitable chord progression along with it. I am not that new to song writing. For a riff of the Pop kind often times I can easily attach a proper chord progression to it. However, when I came up with a more intricate riff, then it seems that at this stage I could only use a chord progression sounding far-fetched here and there. (My major songwriting instrument is guitar, sometimes keyboard).
For concreteness I guess an illustrative example would suffice :). I realize doing this is an art instead of an engineering process that has got an SOP something.