I don't really like most effects enough to find a practical use for them in the context of a song. If my amp had tremolo on it, I'd use it to add some character to a clean tone, but my amp right now doesn't. I use Delay subtly for texture, and sometimes I let it oscillate to add some interesting psych sounds to my playing. I use Fuzz like it's nobody's business. I don't ever turn my fuzz off. I use Univibe on faster paced songs to add some rhythmic pulse. I don't really write songs around the effects though. I just write songs, and if I like the effect in it, I'll toss it in.