You can bend them in, out and make them more anatomically correct (in larger cup sizes, when wires are really wide you may want not only make them more narrow or wide, but also more 3D, to reflect the fact that your ribcage not rectangular with breasts in front of it).
Bend wires gently, slowly increasing pressure and when you feel that they are bending then make pressure even.
Make small steps (like 1/8″ at a time) for each cup in turns, try the bra after each step.
Beware of how straps and band position change. When angle of the ends of the wires changes band, which attached to them, changes its position too. Bending out can make bend slightly angled down and it always makes straps more far apart. But if you are making wires more narrow you should be really careful not to make band riding up, straps position rarely a problem in this case.
If your hands not particularly strong then it could be a good idea to use stronger pair of hands. Just make sure those hands attached to the body with brain and attached in right places (bending too much or with too much strength could ruin the bra). You can’t really control what you do with maximum effort you capable of, and wires usually aren’t very easy to bend.
Here is a good post about bending with photos before and after. But actually it’s pretty much basic alteration. The only problem: some brands have wires extremely hard to bend (Masquerade Rhea wires were just returning to their previous shape, e. g.).
Making wires shorter
Sometimes wires are poking either underarm or at the center, With me it’s usually the later, but it basically the same in any case.
Steps by step instruction
Remove stitching near the end of wire channel from the inside or make a hole in wire channel. Try to be not as sloppy as I was.
Nip the extra causing the problem. This could be hard part, you may need to use small hack-saw.
Here you can see clipped wires’ tips of my Masquerade Rhea: pretty tough stuff: stainless steel and quite thick (ruler is in cm and mm). Wire is about 3 mm x 1 mm or 0.12″x 0.04″.
Apply some silicon on the tip (it can be easily bought in plumbing supplies departments). Wait for it to set. This operation prevents tips from pinching.
Place the wire back and restore channels. Don’t forget to make sure that wires can’t move up in the channels.
As you can see, it’s not perfect, but hey… it’s way better than stabbing! And it’s inside of the bra.