This is a no brainer. Given a tweezers anybody will know how to use it. It just depends on how often you handle it and you will be competent with it over time and usage.
There are various types of tweezers for holding gemstones. The most common one is the simple two prong type with serrated tips to hold the stone more securely. The others are the pearl holders and a stone holder with 4 gripping pincers which is extended by an injector on the top of the tweezers.
Just a few pointers on how a diamond pro handles a tweezers.
One normally holds a tweezers with the thumb and the forefinger. The pinky finger should be placed within the palm with the back of the pinky and the ring finger in between. In this way you can rotate the tweezers to view the stone in every direction.
When you hold a stone use your palm on the other hand as a background. This will give you more focus and you will not be distracted by other background.
To view the stone one would normally hold the girdle of the stone in between the prongs. This way you can view the stone table-top up as well as the pavilion of the stone.
If you need to view the laser inscription on the girdle of a diamond then hold the stone in between the table and the culet.
It is just that simple. Practice makes perfect. In no time you can handle a tweezers like a pro.