I have a drawing of a hand that I have animated using the puppet tool. I have animated the fingers here (different layers) with the puppet tool giving them movement so they go up and down. I have also got light compositions and would like these light compositions to follow the movement of the fingertips. What is the best way to do this?
The best way is to use expressions. You can tie the position of your compositions to the position of your puppet pins!
Not really a good way, I would assume, since typically Puppet pins are not necessarily where you want them for parenting/ linking to expressions, but as @Szalam suggested, start by looking into simple pickwhip expression linking across comps. This may need to be expanded using layer space transforms like toComp() to get correct coordinate conversion and other math, though. Impossible to say without seeing your actual mesh and pins and in fact you may have to re-do it to better work with what you intend to do.
I'm sorry. I'm not sure that I follow. This is a screen shot showing the coordinates of the position of my finger puppet pins.
Place the Lights into the same Comp to simplify matters. Then pickwhipping to connect properties. You will have to perform LayerTransformations in order to connect a Light Layer to the Puppet Pin.
Here's an example to link a Light Layer to a Puppet Pin -
var finger1 = thisComp.layer("White Solid 1").effect("Puppet").arap.mesh("Mesh 1").deform("Puppet Pin 3").position;
var targetComp=thisComp.layer("White Solid 1");