Everyone has their own preference. On my analog board and now on my Helix, I always have my noise gate first (get rid of Fender hum), then my compressor, then my volume pedal . . . and then OD, fuzz, etc . This way the volume pedal increases volume as well as drive into the ODs and amp, like using the volume knob. However, I always place the compressor BEFORE the volume so my cleaner quieter sounds still sound full and smooth. Thus, it replaces the volume knob on my guitar, but after the compressor. I don't like simply pulling back the volume knob on the guitar, which pulls back level to the ODs/amp, but also to the compressor, negating its effect on my clean sound, which is where I really like it. YMMV of course.