There a many ways of holding a coin. But there are three most common ways that you will see in many sleight of hand tricks. It's called palming a coin. There isn't really any skill in palming coins but u will need to learn to loosen up and relax and try to act normal. When you can do that, that's when you will fool the most people.
The three ways in palming a coin are called
#1 thumb Palm
#2 finger Palm
#3 hand Palm
The only thing you need is a coin! Here is how to do them starting with the thumb Palm.
Step 1: The Thumb Palm
for the thumb Palm simply pinch the coin between you thumb and your pointer finger. And you will have just done the thumb Palm!
Step 2: Finger Palming
To finger Palm simply means to grip the coin in you middle and ring finger by curling your fingers around the coin like in the picture.
For the hand Palm all you need to domis place the coin in your palm and grip the coin in your hand like in the picture.