There are many schools of thought on becoming a Vampire and I’ve listed the more commonly believed ones. If you really want to become a vampire and walk the earth eternally as the undead you need to follow these simple steps.
Lead a really bad life. Sinners and heretics and others who lead a particularly deceitful life, committing crimes against humanity are prime candidates to become a vampire. The Church believes that those who die without repenting and receiving last rites are doomed to walk the earth as the undead, preying on those who may still be saved.
Practice black magic or summon some spirits to do your bidding. Summoning spirits or being really good at black magic is a great way to become a vampire. Practice your evil witchery often and just maybe you’ll become a vampire this way.
Become a werewolf, or make one you know really mad. There is a strong connection between werewolves and vampirism. It is commonly believed that werewolves are not immortal, and when they die they return as a vampire. It is also believed that being killed by a werewolf dooms the victim to becoming a vampire.
So there you have it. Just practice your evil witchery daily to become really good at it. If the werewolf is uncooperative, just poke it with a stick a few times to get it good and mad at you.
A word of caution though, leave instructions NOT to be cremated when you die, that would really put a damper on your plans of becoming an undead Vampire