what do you guys mean when you say "make sure there spined right"?
STATIC SPINE is the stiffness of the arrow and its resistance to bending. To determine statice spine, the arrow is supported a two points a known distance apart and a force is applied to the center of the distance, usually through a weight. The amount of displacement of the center point, how far it drops, determines the spine. Arrows with a high spine will not sag as much as arrows with a low spine.
With a compound, I liked shooting paper, that is, a large piece of paper set up to shoot your arrows through, maybe 5-10 yards from the shooter.
When you do this, your arrow SHOULD tear a "perfect" hole, right? It should punch a nice, pretty hole, with the fletching tears in the right place etc.
That's the goal, that's rarely where you'll start at.
Your arrows can rip/tear holes up, down, left and right, and its in large part due to arrow spine (assuming your rest is set up correctly)
Your arrows flex (archer's paradox) when you shoot - but there are some arrows that don't flex enough or flex too much, depending on spine.
You can affect the spine of your arrows by cutting them shorter ( increases spine, you're making them stiffer) or adding weight to the points (weakens the stiffness) or a variety of other ways too.
I'm shooting a recurve, fingers, instinctive, so paper shooting doesn't work well for me. For me, I shoot bare shaft, and I cut 1/2" at a time off new arrows, or I can add weight to the points by going from 125 gr points to 150 to 200 etc .... and there will be one spot (like right now I think I shoot 29 1/2" ICS400 shafts, weight tubes, 5" feathers, 100 gr inserts and 160 gr head) and they are GORGEOUS in flight.
Go to 125 grains up front instead of the 260 I have and I'v just stiffened up the arrow a LOT - and I won't get as good a flight as I did.
Your fletching will stabilize your arrows a LOT - however starting with arrows that fly really well and THEN adding the fletching is the way you really want to go.
There are a lot of spine charts that will give you an idea of where to start on arrow selection/choice