NEVER ever use the clutch to hold a car at a light or on a hill! That means, don't keep the clutch partially depressed to keep it slipping but holding the car. That's the FASTEST way to wear out a cluch plate.
The best way to drive a stick, and I've been driving them for 34 years, is to:
Clutch to FLOOR. ALWAYS to the floor. Put car in 1st gear.
Start to release the clutch while starting to depress the gas pedal. Don't over-rev the engine, and as you release the clutch, give it gas.
Watch your RPMS and listen tot he engine. Once you get up in RPMS, and you are moving, start to RELEASE the gas pedal while starting to depress the clutch. You should NOT be giving any gas pedal as you push the clutch ALL THE WAY TO THE FLOOR. THEN, SHIFT to 2nd GEAR, and repeat the steps to release clutch while applying gas. DO this procedure for the remaining gears.
Clutch pressure plates should last thousands of miles - provided you do not 'wear' out the pressure plate.
"Grinding gears" is the noise you hear when you don't engage the clutch properly, and a highly revving engine with the clutch released or partially released might indicate the clutch is slipping and needs repair.
There are several components, if your clutch is hydraulic.
The master cylinder. It's job is to allow you to impart pressure in the oil to move the clutch fork to pull the clutch away from the flywheel.
The clutch fork is moved by the slave cylinder when you push the clutch pedal.
Then you have the clutch pressure plate itself. When the clutch is released, the spring in the clutch allows the pressure plate to mate up to the flywheel on the back of the engine. FRICTION and spring pressure holds the two together, so the motion of the flywheel is imparted to the clutch and tranny shaft.
The clutch fork sits and pushes on the 'throw out bearing' which in turn allows the entire assembly to 'spin' in neutral. If you hear a 'grinding' or metallic' sound when the transmission is in neutral, and the clutch is released, you have a bad throwout bearing.
That's about all there is to a clutch mechanism. If you are wearing out the pressure plates, you are not releasing the clutch properly or allowing it to slip in some manner, so that instead of engaging and 'locking up' on the face of the flywheel, it is spinning and causing wear and tear on the plate and flywheel. If you do this enough, HEAT will build up and eventually crack the material of the plate itself and it will wear or slip more.
If you get down to the rivets and they grind into the flywheel metal, you are looking at a major cost.
You should examine your clutching methodology and modify it to stop the wear and tear on the clutch.
Remember this rule:
ANYTIME you have to put your foot on the clutch, it should ALWAYS go to the floor. NEVER partial. My dad taught me that and it's never failed me. Always to the floor or not. No in-between or you will wear it out.