1) get good armor so it’s attacks don’t kill you

2) get a bunch of blood packs, dying and respawning with full health is faster than healing it all up

3) actually find one, recommended is a spyglass o and a good weapon or a strong tame to take out the bugs in caves, I usually go to the emerald trench and look for them on the ceiling in the wide-open cave

4) Find a good level and kill its friends. Shooting it with anything will get its attention.

5) DONT ATTACT THE ONE YOU WANT TO TAME! instead, let it grab you and eat your blood packs, this raises the taming bar

6) be careful not to take fall damage, and repeat the grabbing and bam you got a Desmodus!

Be careful out there!