The first thing you have to understand the box system. In a mechanical box, typically 5 levels, which are numbered. Gear shifting takes place while pressing the clutch pedal. So first you need to learn how to properly and time to shift gears. Not a factory car, you need to get behind the wheel and for one hour to methodically switch gears for such a scheme: "clutch - transmission - clutch - next gear" and so on until the last stage. We must not forget that during the shift it is necessary to hold down the clutch pedal, otherwise the switch will not work.
The next step is to learn to understand when to shift gears while driving. The signal for switching is the engine speed. Either by sound or by tach, it is necessary to track the engine speed. Experienced drivers determine the time of switching from the lower to the upper only by the sound. The smaller the engine size, the faster the moment of switching. In that case, if the speed must be reduced, then at the right moment when the revs are at the bottom of the indicators for the tachometer, you need to switch the box into a lower gear. Otherwise the transmission will be increased wear.
As soon as a new driver will understand the basics of gear, it is necessary to automate the process of shifting. This would be the best time of the weekend, when the roads are more loose and while driving it is possible to slow down the speed and to accelerate in using mechanical gearboxes. Also this can be useful for traffic jams when the driver needs to work quickly shift the lowest gear.