Poi is a skill toy. Also poi refers to both a style of performing art and the equipment used for engaging in poi performance. As a skill toy poi is an object or theatrical prop used for dexterity play or an object manipulation.
Poi spinning is a type of object manipulation or performance art. It involves using a set of weights on strings. Many people use beanbags in long socks. These are called a set of poi. People spin the poi around their body drawing shapes in the air.

LED lights or fire is sometimes used to make the poi easier to see and more exciting to watch.

Useful moves with poi spinning 
Walk or jump while spin poi. Do dance moves. Stay in same place but move spin image everywhere and in all directions. Move body with poi or arms. If hands go right, move body to right. Spin slow or fast. Straighten your arms. Add difficulty like for example stay in 1 leg. Lie down on the ground and spin. 

If spinner will make all this moves while he is training some trick he will feel more confident with the trick. Also spinner will learn trick faster, will be able to change this trick to other tricks more easily.

What can help to spin poi 
This can help to make many poi tricks.

 Visualize move that you need to make.

 Drawing simple geometric shapes in air with 2 arms everywhere including behind back and behind head. This will also help to make trick that require spinning behind back.

 Film yourself on camera and watch this video or use mirror. 
Divide trick into steps. 
This can help to make poi tricks.

 Close eyes. Pay attention on how you feel.

 If you try to spin trick in 1 hand, you can make your left hand spin what you need. Right hand do random actions. This will be especially useful in hybrid tricks. Because in this way you detach left hand from right hand. After that left and right hand can do really different moves.

 To make hybrid tricks you can pay 90% attention to what left arm spin and 10% attention to what right arm spin.

What abilities increases with poi spinning 
Poi can develop rhythm, balance, concentration, coordination, grace, body stretches, grip strength, attention  . Some poi tricks like complex atomic tricks can develop skill of solving geometric puzzles.

Where poi spinning is useful 
Besides increasing abilities, poi can be useful like a physical activity. Physical activity increases when spinner spin much more heavy poi, spin fast, add body moves.

Poi can be used as art of drawing shapes in the air. This can be done by taking photos on exposure when spinner spin LED or fire poi.

Spinning more than 2 poi 
When spinner grab 2 or more poi in 1 hand he can have 3 poi or more poi in 2 hands. 

This can be useful in these cases :

 When spinner spin 3 poi this can be useful in 3d tricks when each poi spin in different plane. For example 3 poi spin in 3 planes when each of 3 planes are parallel to different face of cube. These 3 planes are called face plane, wheel plane, helicopter plane.

 When spinner spin 4 poi and he grab 2 poi in each hand. Each hand can make tricks similar to butterfly trick.

How to divide trick into steps 
To divide trick into steps will help you to make it. You need to select and remember all positions of each poi when some of 2 poi is at most bottom position. Let's say trick is repeated per N bit cycle. Between beats of left poi there is time T. Lets say left poi head is at most bottom position at moment M1. So you can select dots of both poi heads at moment M1. Next moment M2 be after time T/2 because poi move in split time. You can in same way select dots of poi at moment M2. Each new moment will be after time T/2 relative to previous moment. In all trick cycle there will be 2N moments. at moment Mx poi head is at position Px and have diction Dx. x is some number. At moment M3 position is P3 and diction is D3. At any moment Mx there will be direction of movement of poi. This direction is like arrow in 3d space or vector. 

For example, for 3 bit wave there will be 6 moments. For 3b wave you will have 6 position and 6 directions for each poi head.

When you spin trick, you should pay attention to each moment and at each moment pay attention that poi heads moves in correct direction.

Different types of poi 
 Fabric poi . For example, striped sock poi can stretch more when speed of spin increase. Striped sock poi prevent tangling of 2 poi. When 2 poi accidentally tangling spinner may not spin his trick anymore and all trick fail.
 LED poi. Can have different mode. Each mode have unique drawing from different colors. podpoi 2 is a type of LED poi where many different poi head are synchronized via wireless connection so that all they will change mode synchronously and in smart way that will look interesting. When many people spin podpoi 2 together mode of each spinner will change in 1 moment.
 Pixel poi. They draw image in air. For example image can be some photo of human face.
 Fire poi. They are usually set on fire after soaking in kerosene. Different types of fire poi are monkey fist, twister, cathedral, block, mura, weka.

Other websites 

Performing arts