I've done this before in VFR mode. It's very easy to overshoot the airport. The only suggestion I have is setting this flight to IFR-you won't overshoot the airport because ATC will tell you if you're not descending fast enough; it won't tell you to slow your airspeed. When I descend, I do slow my airspeed as do real airlines when they descend; one will feel the aircraft slowing. I have found that in VFR, at higher altitudes, and depending on the airport's elavation, I start my descent about 120-130 nm out. I also open my GPS just to make sure I don't overshoot the airport. Not sure if I helped with your question, but I hope I did a little.