hi bud_wiser,
when i write, i wont force a song just cos i haven't done one in a while...let it come naturally.
they say that minor chords make a song bluesy or ballardy, not necessarily...
so, a good story teller can look around him and make a story from what he sees, eg: my son has been having a lot of problems with his girlfriend, which he wont dump! but i've got 4 or 5 songs from it!
a friend had problems with a woman he had strong feelings for, she was unhappily married, another song.
i once saw graffiti on a wall saying "tracy loves paul" yep you guessed it, but i binned the song it was rubbish! so dont expect everything you write to be the new "bohemian rhapsody" you've got to write crap to know when you've got a good one.
as for performing, if your going to do your own songs, which are [in your words] "gloomy" do a couple of up-tempo/up-beat covers. break the night up.
hope i've helped
phill