The way you hold and attach your yo-yo to your hand is very important. If you don’t attached the slip knot between the first and second knuckle of the middle finger on your throw hand you will lose a lot of your control over it. Putting the slip knot too close to your palm (between the second and third knuckle) will make it more difficult to throw the yo-yo and do the intricate tricks you will be learning later on.
The way the yo-yo is set in your hand is also very important. If the yo-yo is upside down in the palm of your hand, you will not get a lot of control of out it when you throw the yo-yo. The way to know if the yo-yo is right side up in your hand is to look at the string. If the string attached to your finger rolls up along the top of the yo-yo then you are holding it correctly. This way, when you throw the yo-yo, it will roll easily out of your hand down the string, and when it returns it will automatically be facing the correct way if you catch the yo-yo correctly as it winds up. If the string is going across the bottom of the yo-yo (the wrong way to hold it) when you throw it, the yo-yo is likely to flip over, causing it to descend at an angle making it difficult or impossible to return to your hand. The reason for this is simple physics; the yo-yo will try to flip over, wasting much of the energy you have put into the throw. When it flips over, the yo-yo is likely to be spinning at an angle, causing the string to rub against the sides of the hubs of the yo-yo. This will cause it to slow and tilt further, usually resulting in the yo-yo spinning out of control.