Well, I used needles from a tree that wasn't mine. So I used only new growth, the tips, and I only cut half of the needles off. Apparently if you cut more than half off you stunt the tree.
I felt pretty silly giving a haircut to a tree in the church yard but I just tried to ignore the passerbys.
I pretended they were hops and soaked about 3 oz of them in bourbon for a month or so.
If you google "eating pine trees" you'll find a lot of survivalist stuff about how to eat a pine tree. But take what they say with a grain of salt as some of the sites I saw show picture of trees that aren't even pines