Reading this DIY in preparation of installing my coilovers and didn't see this mentioned anywhere (I may have missed it). But I think you will want to tighten bolts 1 & 2 in the photo below with the suspension compressed at ride height to avoid undue stress on the bushings. FYI an easy way to simulate ride height when the car is on jack stands is to use a hydraulic jack to load the suspension to the point where the car just begins to rise off of the stands.
As far as the other bushings that may not need to be loosened to R&R the springs. Is everyone loosening these as well and re-tightening at the new, lowered ride height? Probably wont hurt since I will be doing an alignment anyways. Didn't see torque specs for these though.