During the startup, taxi and takeoff section of the flight the actions of the pilot are based on numerous variables and his/ her ability to process that information and take sound decisions based on that. During taxi and cruise, pilot workload is usually low and the situation is relaxed.
When cruising to the destination workload is relatively low. For the average VFR pilot this means he/she can converse with his passengers and relax while scanning for other aircraft and keeping an eye on the onboard systems while talking to ATC should that be needed.
When the destination gets closer it really helps to prepare in time for the upcoming descent and landing. This minimizes workload during the actual approach and keeps safety at a high level as the pilot will probably be a bit more tired than at the beginning of the flight.
Fatigue is an important factor for the pilot. At the beginning of the flight he/ she is rested and fit and be capable of handling the workload. During the flight the pilot is under a certain amount of stress due to controlling the aircraft, flight monitoring, navigational issues, engine noise and vibration, all of these factors add to increase the level of fatigue.
A graphical representation can be seen in the image to the right. It shows that the safety margin reduces while the flight progresses. As long as the requirements of the flight does not exceed the capabilities of the pilot, flight safety is not going to be an issue.
To be able to handle this the pilot must prepare for the upcoming task during preflight and do this while still in the cruise phase of the flight.
As you get nearer to your destination you will at some point need to leave cruise altitude. There are several ways to do that: a gradual cruise descent at 500 fpm, steep descent at 1000 fpm or even faster if required by ATC, other traffic, weather or terrain.
Descending at 500 fpm can be accomplished easily by reducing the manifold pressure by an inch or two (or 100 to 200 RPM if flying with fixed pitch propeller). This really depends on the engine/ propeller combination. You will need to experiment a little during turbulence free conditions to learn how much reduction is required to setup up a stable 500 fpm descent for your aircraft. When you initiate the power reduction there will be a few pitch oscillations but with practice you learn to dampen these too.
Example: you are flying at 90 knots and you need to descent from 3500 ft to 1000 ft circuit or pattern altitude. Thus you need to figure out when to start the descent: At 500 fpm it will take five (5) minutes to get at 1000 ft. At 90 knots (1,5 mile/min) you need to start the descent 7,5 miles out from the point you wish to be at that altitude, assuming no wind of course.
Make sure that you have the airplane trimmed for cruise speed, this will result in the same constant airspeed descent. Making life a lot easier for you.
Air cooled piston engines are prone to shock cooling, but only when they experience large power fluctuations in short periods of time. An easy cruise descent at 500 or even 1000 fpm with minor power adjustment and assisted by a gear extension (increasing drag and therefore power) is nothing to worry about in terms of engine shock cooling.
Getting closer to an airport means entering the critical area and this time in the reverse order as when departing an airport. See previous article here.
Before entering the critical area make sure that you have everything setup. Get the approach, landing and taxi charts and work the checklist so that you are up to the task at hand. Basically: get ready for the final descent. If you need to set up navigation equipment for an instrument approach then this the time. Touch each and every one of them while you set frequency, identify the station and set the OBS. Verify the directional gyro with the compass.
Start to listen to ATIS and other traffic to get the big picture, then contact ATC well before entering any controlled airspace. Brief the passengers before you enter the critical area and explain that you will be busy until after landing, taxi and engine shutdown at the parking position.
Some airports, notably larger ones, will have a ground controller which you will need to contact after exiting the active runway. You can setup that frequency in the standby mode or in a separate radio (COM2) beforehand which makes switching really easy and fast.
After landing and leaving the runway, work through the after landing checklist (most items require you to 'clean up' the aircraft) and have the taxi diagram at hand should you need that; contact ground control and request your parking position. When you get there follow through the shutdown checklist and verify each item.
Welcome to your destination!