How should I place the lights?

You can place your lights as you prefer, there is not a rule!

Decorate your tree, than, thanks to the mapping procedure you can create a precise map of your LEDs and apply effect with the maximum impact.

A good advice to obtain a good visual is to place the LEDs on the surface of the tree.

Some LEDs may be hidden to the camera, worry not, the algorithm will estimate their position, allowing a precise application of the effects.