You've got plenty of good advice here. I'll add that you can also manipulate the dynamic spine of an arrow by using footings and a fletch wrap. For my set up, a fletch wrap on my axis trad 500's required a 3/8-1/2" longer shaft for the same tune, versus no wrap. Adding any weight to the rear of the shaft will stiffen the arrow, as will adding an aluminum external footing.
Another trick that I use on my axis shafts is to use double HIT inserts. It can be tricky to install, but it works great to stiffen the shaft as well. And by placing the added weight in the shaft behind the point (internal footing), instead of all the weight on the point, it doesn't weaken the shaft. You get added weight and FOC, and stiffen the shaft at the same time.
You can use a combination of 50,75, or 100 grain inserts to achieve your desired weight and still use the broadhead weight of your choice. I'm sure the double insert trick will work with the aluminum inserts as well.
I use a Q-tip and denatured alcohol to clean the inside of the shaft, and a rag with DA to clean the inserts. I heat one insert so that the blue hot melt cool flex, melts easily. Use a generous amount on the first heated insert. Push and twist it into the shaft until there is 1/8" left sticking out and plenty of excess hot melt. Grab the next insert and finish pushing and turning the two inserts into the shaft, again stopping with about 1/8" left to wipe the left over hot melt off on a rag. Then use the insert tool to set the proper depth and go straight to the cold running water. You have to be quick with this process though, because it's a big pain to remove them and start over. It's really not that difficult once you've done it a couple times. I've used this method for the last two years, and have not had a failure yet! (Knock on wood)
My finished arrow is 29.5" bop, 7" fletch wrap, 3 4" parabolic feathers, 150 total grains HIT brass inserts, and 125 gr tips for a finished weight of 569 grains. This arrow flys well out of a few different bows, but was originally tuned for a 51#@28" Javaman Elkheart. I draw just over 27". It also tunes perfectly to my Stalker Wolverine static tip 47#@28"