How to start a design procedure?

Depends what you are going to design (product, process, experience, etc...).
Question can be better answered if it were more specific.

to design a product first understand the customer requirement.
if it is going to be subcomponent of an existing system, you need to understand the load cycles and forces coming on to the product and operating environment etc., so to start a new design we have to doQFD and follow GATES process.

in the first we distributed all items ( socket, lighting, machines, air conditions ..... ets )

 

study type and how start & runining every loads

 

devided our loads Depends on use ( continous load & non continous )

 

collected our loads from end of panels up to MDB or  EMDB

 

design every panel Separate

 

design MDB and transformer and R.M.U

 

that is for L.V. system 

 

also for L.C.  system every location we start study how to use, after that we will distributed all items ( fire alarm, camera, scada, TV, nurse call, .....etc) this distribution it Depends on using area