For low cost fuel, the credit card self serve fuel pumps are on the NorthEast Ramp. East of 15/33, and across from Mukenschnabl's hangar.
Most passenger pickup is done on the West ramp underneath the Tower at DuPage Flight Center.
If you are looking for flight following from the West or North, Chicago Approach in that area is 120.55. If you are coming from the South/SW, it will be 133.50 and they will likely leave you on that freq until handed to DPA tower.
Not much to say about DPA itself. Nice airport, big runways, no obstructions, several ILS.
On departure - just be aware that if you takeoff on RWY 10, and climb aggressively, you've got ORD's Bravo airspace looming above.