This is the process I have followed to get my campaign up and running.
By following these steps you have a template which helps focus the mind and channel creativity. I've found it of immense use in avoiding drift.
The gods of Law must be strong on this Plane!
1. Have a starting base for the characters. Generate a settlement that will act as the PCs home and safe zone. This should be a large village, small town or military stronghold.
2. Have at least one defined place of mystery nearby within 15 miles of the base
3. Generate the starting hex by establishing the dominant terrain. This will be 15 miles and divided into 3 miles sub-hexes where specific terrain is generated per DMG p173.
4. Create the Player Character starting party using the tables in DMG p175-176.
5. Generate the Inn that the characters are based in with a compliment of patrons and occupants
6. Establish the first adventures and missions using the adventure generator in the local and surrounding area.
7. For the initial adventure perform a delve in the local place of mystery as the first mission selected
8. Once the party has completed their first adventure the campaign should develop organically with selection of missions from the adventure / mission pool in the Inn and from the settlement’s inhabitants
9. Run a calendar system to govern the passage of time in the campaign. Don’t extend too far forward for any character or group. Advance this in line with the passage of real time. Start new character parties to fill in for down time and gaps. Use interactions and discoveries to shape the campaign and develop the world setting.
The last of the core books. Power to the pig faced Orc!