pick a spot on the ground about 1/2 mile away (880 yards, ~800 meters), you want to be 400 feet (122 meters) above the runway elevation over that spot, pointing at the end of the runway to begin your final approach. That will give you an almost perfect glide slope, and sufficient time to stabilize your approach. (in practice, since it's hard to estimate distances without a reference, many small airports have a runway that's 800 meters, so you just use that length off the end of the runway, if your airports runway is 1600 meters, use half the distance, etc.)
"many small airfields have an 800m RUNWAY? Bloody luxury..... here in Germany we get 500m.... tops......."
Just joking, so back to reality - fortunately in Germany we have AIPs which have the circuit indicated clearly to ensure noise abatement is adhered to.... Just have to have your iPad / iPhone / Android running Air Nav Pro or similar, you can then easily see when you are expected to turn from downwind to base and base to final.......