Start with how you best want things set out when everything is finished. Where do you want your sockets, do you want to mount a TV somewhere, do you want to keep the fireplace bricked off or do you want to put some shelves there, what do you want the wall to be covered with.
Then you can work out how to best get to the finished product. E.g. spending a whole weekend putting up timber studding and cladding with taper edge boards may seem a lot of effort, but it makes putting sockets and cables where you want then childsplay and may actually take less time than doing the job in little bits and fiddling with stripping off wallpaper/filling the wall, etc. plus you end up with a nice straight wall, noise insulation from neighbours, all the stuff set out the way you want it, etc.
In the long term you won’t regret spending a bit more effort doing it properly first time.
The bodge i’ve seen done (improperly) is to wedge the cable between the floor boards and the new skirting board.