What I use is change-in-altitude (in thousands) multiplied by 3 for the distance back to start the descent. You can add whatever factor you feel appropriate to that - if I have to go to the opposite side of the airport to do the approach then I might subtract from that but if I'm doing a straight in then I'll add maybe 10 miles to get slowed and configured for landing.
E.g., you're cruising at FL280 and landing at 1,000' ASL. The equation is: 28 - 1 = 27 x 3 = 81 nm.
For the descent rate don't worry too much about it - your GS will constantly change on the descent. To get an estimate of what descent rate you need use: GS x 10 / 2; or GS x 5.
Throughout the descent check your flight path by verfiying you're still on a 3 degree path. As you pass through FL200 you should be 57 nm from your destination (plus your factor). At 15,000' you should be 42 nm back. Then adjust your descent rate as appropriate.
With a little practice it becomes easy. I don't bother at all with a wind correction factor.
Last edited by Virtus; 5th May 2013 at 20:44.