You should adjust the yo-yo string to your body height, otherwise the yo-yo would hit the floor when you throw it.
Lay the yo-yo to the ground and cut the string on the height of your belly. Then make a loop at the end of the string.

Put the string through the loop, so you get a slipknot and you can attach it to your middle finger. So the string can not move.

Hold the yo-yo in your hand, so that the string is winding from above to your middle finger.

Throw the yo-yo with a backhandthrow down from your wrist, giving it some drive.
As the yo-yo is in the lower position, turn your hand, to be ready to catch the yo-yo.
For yo-yos without a clutch a little tug is needed, to get the yo-yo back to the hand.
To get a yo-yo with a clutch into a sleeper, it is important to get the optimal drive (rotation) and a little ease as the yo-yo is going down.

The sleeper is the basic trick for stringtricks. Here is a video of the sleeper.

To wake up an unresponsive yo-yo, you need to do a bind.

To wind up a free spin yo-yo, you can not just wind the string over the axle. Due to the free spin you would wind up forever. To get enough response for winding up, you first have to put the string also for a few rounds over your finger. Then just let these loops go and wind the string up. Here is a video.

With the Thumb Wind it is even easier.

Never throw your yo-yo against persons, animals or fragile stuff.
Check your string always before playing. A yo-yo with a broken string can harm people and other things. And your yo-yo can also break.