Engine and its oil. Use DTSi engine oil
Check the engine sound. Rough engine handling leads to weird engine noises and heating up of engine. This will reduce performance and mileage

Brake shoe of rear break. This must be check , because, it gets destroyed if you do sudden pressing of back brake pedal frequently

The oil used for front disk should be replaced when the time is appropriate

Change the clutch operation to half clutch. Any mechanic will perform this. So in this case a light pressing of clutch is required to change the gear. This makes driving easy and also improves mileage.
Clutch is a mechanical device. It transmits power from one element to another. Refer the diagram given in annexure.
In automobile, the engine is the prime mover. A flywheel is connected to engine. The clutch is connected to transmission. When the driver is pressing clutch pedal, clutch plate is pressing the flywheel. Fly wheel motion is transmitted to the transmission system. When driver presses the clutch pedal, the clutch is disengaged from the fly wheel, so even is engine gives rotation to fly wheel, it is not transmitted to transmission system. That is why, driver presses clutch pedal and changes gear.