the shape of your toes will decide what kind of box your shoe will need. personally, i need a very tapered (kinda pointy) box as square boxes hurt my feet and if i danced on them it would cause severe injury. the height of you arch will decide what type of shank to get. a super high arch will need a different strength shank (which is the sole) than a flatter arch. the strength of you feet will also determine the shank strength, so make sure you are strong enough to start pointe work.
you also want to make sure that your ankles are aligned as shown above.
Here are some diagrams to help you better understand your pointe shoes
The Great Drawstring Debate
many dancers aren't sure whether or not to use the drawstring on the shoe or pull it out completely. honestly, it depends on the dancer and what feels good to you. don't buy a pair of pointe shoes for the sole reason that the drawstring is easier to pull out. i have tried it both ways and while i personally prefer to keep it in, many people have their own opinion when it comes to their shoes.
the vamp of the shoe is the part that makes you taller when you go on pointe. having the wrong size in your shoe can seriously injure you. always make sure your pointe shoes fit correctly by making your all toes are flat on the ground when standing flat footed and that they feel snug but don't pinch.
My Shoes <3
I use russian pointe shoes, which are known for the very taperd boxes and the very light, almost white satin colour. i specifically use the aleksandra model, because those are the ones they have in supply at my local dance store. (totally kidding, these just work best for me and are pretty cheap) i understand pointe shoes can be expensive, so dont just go and waste your money on a pair that don't fit or will give you trouble. IT'S NOT WORTH IT! trust me
Stay sparkly <3