When editing a Airbase (any airport) the start is usualy with some research about the Airport data like Runway coordinates, Airport Lighting including Runway Lighting, Ramp and Spawn names, availability and usability of Satelite imagery, IFAET Database check, and so on.
When all this prework is done, you can start editing.
As an example I will show the different parts of editing as screenshots in their order down here.
eg OEKM King Kahlid Airbase in Saudi Arabia.
starting with Runways
those given, the satelite imagery can be fit to match those position precise in order to match the navigation data like approch fixes in IF later.
I keep of the satelite imagery in the following.
boundary and tower view are next
after that I add the pavement like,
resulting in a whole pavement:
now we are going for markings, starting with the Sidelines:
Sidelines with pavement shown:
followed by the hold lines:
After that I start with the Taxiway Centerlines.
Beginning with small ones like hangars and small aprons.
with some small ramps:
followed by dispersals taxiway lines
The large Bravo Ramp:
and finaly the main taxiway centerlines:
giving this result:
now adding the road markings
finaly the spawn positions:
all combined it looks like this:
what you see as layout in the IF Map is this: