The type of roofing project you need all depends on your needs. If there is a hole in it, then finding the hole and understanding the extent of the damage should be your number one priority. If it has suffered external damage as a result of storms or bad weather, then identifying the root of the problem by accessing the exterior should be considered.
Furthermore, you need to know what type of upgrade you want. Do you want to merely fill in a hole or go further and undertake a complete overhaul of your roof? Alternatively, if you need to install or move satellites, then finding out the proper planning procedure from your local council should be done before any work begins.