I spent many hours reading most of the conversion threads here, and I plan to borrow a lot from those. Bear in mind I'm barely started on my project.
For anything you want to start doing with the bus, think to yourself "will this interfere with doing something else later?" If it will, then consider waiting until the other thing is done. Also think to yourself "can I do this before I've done XYZ?" If not, then do XYZ first.
It can seem overwhelming at first. Just break it all down into sub projects, and decide what order they should be done in.
If you go with a low energy approach to living in your bus, then you won't have much complication with the wiring in the first place. However, it will probably look nicer when done if you leave channels behind the walls/ceiling for wire runs that you anticipate having to do.
In any case, just jump in and get started and it will work itself out. A little bit of forethought will help avoid the situation of undoing and redoing work. However, no amount of forethought will help you avoid all of those situations.