Firstly, you need mutagen, and a lot of it for a high level. On my 5X taming servers, it was roughly 4% per feed.
To actually tame them, you need to do the following:
1) find the creature. They are always in space, and have the most probability of appearing at the top of the spawn zones in Space. Look around the asteroids at the North and South ends, that's where I tend to find them.
2) you need to take it down to below 10% of it's health, where it will start glowing blue. It's breath attack is annoying because it stuns you for 5 seconds, and it breathes on you like a person with Halitosis does on the bus.
3) once it's health is down, you need to get close and ride it like you would an equus. The mutagen should be in slot 0 because every time it does a "barrel roll", you should be feeding it.
I haven't found a way to not get bucked off 2-3 times, depending on the level, and if it aggros Astrodelphis, they can slow you down and allow it to get away and heal. It heals pretty fast, not as fast as a reaper though.
Using the creature... It's a Tek variant wyvern. It's breath attack doesn't seem to do damage, but it has a stun effect that let's you get a few free chomps. The longer you hold the breath action button, the more stamina you burn, so only hold it long enough to immobilise your victim
Contrary to what you may hear, the Voidwyrm is one of the simplest creatures to tame in ARK. The issue is attempting such a thing without decent bait and strategies.
Now for the tips themselves, so here we go:
1- Humans don't make good baits. We have relatively low health and can't shoot while stunned. Spoilers: You need to hurt the Wyrm, oh, and it also can stunlock you to death if you are not careful enough. Tames with high HP (20k+) and OK saddles (40+) are enough to even the hardest hitting of their tames.
2- They can and will destroy all kinds of structures. Trapping them with man-made structures is almost impossible, and baiting with structures is impractical, unless you get lucky enough to trap them a corner. Another spoiler: They not always spawn near natural map structures, and kiting them isn't very pleasant...
3- They can steamroll your precious Hover Skiff. Any and all Voidwyrms instantly destroy Hover Skiffs, no mercy will be shown. As Skiffs are the fastest way to search for such a (now) very rare creature, it's advised that you tame them where they spawn, and place your Skiff away from the area.
4- They take reduced damage from TEK weapons; This, however, can and should be used to your advantage, as they need to be brought at very low health to be tamed. Below 10%, to be precise.
TL;DR: Let your creature tank it, carefully shoot them, mount when ready, use Mutagen when they roll. Repeat any of these when needed if bucked off.
Finding them is now the real pain. If you use the Wiki Spawn Map, uncheck the "Space_Gen2" box. You are VERY unlikely to find them in these areas. To the ones that don't: stay to the West of 50 Longitude.
In any case, try to stay at more or less the level of the bridges.
When you are taming these your actual character has to damage them before you can mount them to begin taming. Your dino comes out brings it below 10% health and then you must damage them to be able to mount. A single punch worked for me when I flew up to it after I had brought it below 10% health with my dino.
How I understand this, u need to lower its health and that is insanely hard because they have CRAZY health regen but I find it best to use a decent level snow owl as the bait/sacrifice and with a tek rifle just beam it till the blue jets show up on its back then tek boost over to the Voidwrym jump on its back then feed the mutagen when it barrel rolls