While I'm still new to the whole songwriting thing, I still want to share how I go about doing it. Over the last month or so, I've had a vastly increased amount of inspiration, both for lyrics and for melodies, and obviously they get treated in different ways.

For my main-project(s) right now, I started out with finding out what notes/chords I wanted to use, and how I wanted to use them (arpeggiated, strummed or both). This resulted in the main riff of one of them being only 4 very similar chords (all based on the B-Major Barre Chord, simply moved around on the same strings), first sweep-picked upwards, then every note played individually in the same direction, because I think it gives a nice over-all sound with the right settings on my amp, especially when the Lead guitar-line is played on top of the main-riff. I've not really put any lyrics to that song yet, but I won't force lyrics unto a song, as I believe that has the potential to turn a potentially great rock-song into a first-class mess.