Using ice cube trays is a good way to organize screws. Use 1 cube per step. If you have enough, dedicate 1 spot per step/size of screw.
Even better, but a little more money, are the clear multi cell parts boxes. That way you can close the box to secure all the parts in order (even add notes) in case the project has to be interrupted.
Also print out a hard copy of the disassembly guild and MAKE NOTES is you proceed from step to step.
When in doubt, PAUSE!
Take pictures along the way. Re-routing cables is a lot easier if you can see how it looked before began the carnage of disassembly.
ALSO! When frustrated, TAKE A BREAK rather than causing one.