[Boron]

In Vanilla the best way to bloodhunt is to clamhoard and wish for blood.
As a side effect of this strat you will search your lands with accashic record, thus if there are any sites with boni to alteration or blood you will find them and they will further speed up your rapid growth of power in lategame.

For this strat Ryleh and Pythium are very well suited.
You won't have blood till something like turn 60 but after that you will swim in blood. With 4 wishers you get e.g. 1000 blood per turn.

For conventional blood hunting i now like mictlan most. Just do gather 200-300 slaves, patrol a 20k population province and hunt with 15-20 priests with sdrs.
After something like 20-30 turns this province will be reduced from 20000 to something like 3000 population and you have to move on but this way you have only to hunt in a few provinces and not in many.
Mictlan is basically the only blood nation which can do this kind of patrol+bloodhunt.
If you also do a bless strat you can use your money on the excellent mictlan sacred troops.