They say that a great riff comes from the tunes in our heads and that's exactly the case with my riffs..not that they're great but they are amazing (love your own). How do I make riffs? Simply complicated. The simple part is just playing what I can play. Sit in one corner, setup everything, bang on! A riff would just come out from whatever I can hit on my fretboard. If I feel doing a sustained power chord then drop some squeals then shred then mute then do a walking bass then make some noise, I will do just that. When I feel wasted already and the song seems to be dragging to nowhere then I'll stop. The complicated part is that I cannot go back and do the same riff! It just spawn something else! That's why some of my riffs seem to be just like the other. Even if I have recorded the riff and even with a video, I just cannot do the exact same riff. The good thing is, well, I am happy with what I have made.