Turn your EAGLE schematic into a PCB

Step 8 Check signals to see how they'll route

One way to get hints on part placement is to look at some significant signals to see whether they have nice straight paths, or whether they zigzag all over the board. First use the RATSNEST icon/command to have EAGLE recompute the airwires. The way things are now, I have nice straight connections from the transistors to the lamps, but if I type "show gnd" in the command line, I see that this is at the expense of making the ground signal zigzag. So I swap the transistors because GND is more important to have straight. (IMHO, YMMV, etc.) (This ends up putting the transistors near the supplies that they switch, rather than near the lamps that they switch to, so that still makes sense from a circuit point of view too.)

After the rest of the components are placed in ok-looking relative locations, I can squeeze them together again (manually, moving them one at a time; no magic command for this!) and shrink the board outline some more.