Descent

Holden Riley has left a very informative comment about descending! Thank you very much, Riley, for sharing.

For planning your descent, there are two simple equations that you can use to get you almost all the way there and work every time if you do the calculations right. You can usually use the cruising period to do them and it is really helpful to have a pencil and paper, and maybe a calculator if necessary.

1. Rate of descent or VS: Take your GS, the speed that you are going while you are cruising, and multiply it by five. If you cruise at 360 kts, your VS should be 1,800 fpm and if you cruise at 150 kts, your VS should be at 750 fpm.
(If you're flying an airliner, your VS should be lowered to 1,000 fpm once you are below 5,000 feet and then adjusted accordingly until it's around 600-700 for the glide slope on final approach.)

2. Distance of descent start. It's important to figure out how far away from the airport you have to be when you begin your descent, that way you don't over shoot the airport and have to go around. To calculate the distance needed is easy, you just take your cruise altitude, divide it by 1,000 and multiply by 3. If you cruise at 30,000 feet, then 30,000/1,000= 30, and 30x3=90, you begin your descent when you are 90 miles from the airport. 20,000 is 60 miles, 15,000 is 45, and 10,000 is 30. (The part that you might need a calculator for is looking at your flight plan counting the miles and figuring out where that point is, so you can begin your descent at the right place. That part also takes the longest time to calculate so make sure you have enough time to do it. It would also be smart to write down so you won't forget it.)

A perfect approach is difficult to achieve but this will certainly help you out.

Also in a descent and approach, these are the specific Airline based guidelines followed by professional pilots around the world:
10,000 ft: landing lights, strobe lights, and nav lights on. Flaps retracted. Airspeed between 200 and 250 kts.
8,000 ft: Flaps between 1 and 5 degrees.
5,000 ft: Flaps between 10 and 20 degrees. Airspeed between 190 and 225 kts. 1,000 fpm VS.
2,500 ft: Flaps between 20 and 26 degrees. Airspeed between 185 and 195 kts.
When you are five miles out, gear should be down, flaps should be fully extended, and spoilers should be armed.
On the glide slope: (if you have the visual boxes for help on final approach, that is where the glide slope starts.) Depending on your weight and weather conditions, you should be going between 145 and 165 kts. Trim should be as required. The autopilot should be disengaged except for heading, unless you have crosswind, then the whole thing should be off. Autopilot should have these settings but should not be armed; SPD 200, HDG (between 0 and 359), ALT 6,000, VS 2500. If all goes well you wont need any of those settings. The thrust levers should be manually holding you at your approach speed, but when the call out computer announces that you are at 20 feet, you should bring them back to idle (0%) and flare. Wait until the nose gear is on the ground before adjusting to the center line, and applying reverse thrust. At 60 kts, reduce thrust to 50% and wait for the auto shutoff. DO NOT USE BRAKES, those are for parking only.

Taxiing: Use the rudders to turn, never use engine power to taxi unless you are heading against wind and the plane will not budge or is having trouble turning. Remember, 25 knots to drive, 10 knots to turn.

WARNING: Autopilot should never be used to slow the plane down by more than 10 kts. Bring the thrust levers down to 20% to 25% with the auto-throttle off and put spoilers in flight mode if you have to. Then rearm the auto-throttle when you are at your speed. Make only small adjustments and make sure the spoilers are closed when the auto-throttle is in use.