Before any of the first fixes are done, you need to make sure that all the chasing in the building have been done for all your electric wires and plumbing pipes.
This is one part of the project that many people who know a bit about DIY and have a hammer and chisel try to tackle themselves, thinking that they can save a few Euros on the project. But in most cases as soon as they start, they wish they had never attempted to do it in the first place.
Chasing should be left to the professional who have proper equipment to do the chasing and know the proper ventilation process in order not to suffocate themselves.
If you value your health and lungs, do not attempt this yourself, or at least make sure that you have proper respiratory equipment.
This is another part of the project that you need to plan properly as it can not be changed later on without causing damage to the finishes and creating more problems.
You need to decide exactly where you want all your light switches, sockets, wall lights, plumbing pipes, phone lines, computer networking, tv/satelite and any other wire or pipe that has to go into the walls. And do not forget the security lights for the outside walls.
You need to decide on how high or how low you wish the access points be to them and before the chasers arrive you need to make sure that you mark all the locations clearly where you want them to be placed. Do not leave this decision to the electrician, plumber or the chaser as everyone has a different idea on their placing.
When you are making the decision on the position of these access points, do take into consideration about the reach of the children or people who are handicapped and would have difficulties with certain heights.