Here are a few things that occured to me...
1. Try not to touch the injured part of the kitten,it may hurt her even more.
2.Offer it water and food,but if it refuses don't force her.
3.When you see it lying on the ground,injured,don't come running towards it as it may intimidate it further.
4.Try to place her on a safe place if it is lying near a road or where vehicles are moving.
5.Try to sooth it by rubbing its back or area aroung its head.This will make the kitten realise that you guys have come to help it.
6.See if its wound is one of that bleeds.If its wound is bleeding,then tie a dry cloth around it,neither too tight nor too loose.
7.If its wound is one of internal bleeding,like getting hit by a heavy object or falling in an awkward position from a higher spot,then the most you can do is,put the cat in its normal lying position if it is lying in a twisted and an unusual way.
8.Observe the change in the kitten's reaction when you patt her.If it is lying down calmly and has closed the eye,that means she is a bit relaxed.
9.However you can always take it to an animal specialist and it her cured.
10.The tenth is in your appreciation, if you even make an attempt to help an animal in pain,you really are a very kind boy.
Hope that will be helpful. :)