The first step is to plan out your design. We did this on some graph paper. EL wire is stiff and holds its shape but can't be bent many times or it will break (like any stiff wire). For that reason, you'll want to try to try and keep the wires on large flat surfaces or going around edges that don't flex.
The nice thing about most laptop bags is that they have a flap and pockets with strong piping and corners to protect the computer, we'll take advantage of that! We're going to put a design on the large front flap, we'll start by chalking it out.
Think about how you want the EL wire to travel around the bag. EL is hard to solder to, and harder to 'split' so keeping it simple is key! You'll want to have all the ends terminate near a pocket that will hold the inverter.
Since the pocket AA inverters can only drive 2 or 3 meters or wire maximum, its smart to keep the design short and sweet. Keep track of how long the final wire will be, add up all the segments and keep the number under 2.5m for the best look. You can also of course use a larger inverter or two inverters!
A half hour of planning now will make eveything easier later!