I've bowhunted for nearly 3 decades now and STILL can't find a need for mechanicals so can't help you with those. But for regular fixed, they are mostly steel and aluminum so they should last a lifetime with the basics of care. Keep them sharp and away from moisture and other than that, there's not alot to them. After you sharpen them you can essentially make them "moisture proof" by sticking them into a large candle to cover them in wax. I know guys who likewise paint theres and I suppose that'd be just as effective. Stainless DOES rust btw, just not as easily or visible so keeping moisture off of them is equally important. I prefer carbon steel vs SS because it's easier to resharpen and put a sharper edge on them but it's tougher to find carbon heads that fly well if you are using a fast vert/xbow.

If your bows quiver has a piece of foam in it to hold the heads then make sure and remove it or try to at least dry it out after a hunt in the rain. That's where alot of guys get into trouble, they dry their broadheads but never think about a wet quiver so they stick them right back in there and that's no different than sticking your knife in a wet sheath!