Mictlan versus strong independents?

[PvK]

Note that you have national demons available from turn 1. Combine a few of the most formidable of those with a bunch of blessed eagle warriors (even if you don't have great bless effects, because blessed eagle warriors can fly), on hold & attack rearmost. Works rather well against most independents and AI's.

PvK

[General Tacticus]

Use slaves or the cheapest warriors as a first line, to attract arrows and take the first hits. Try to get heavy infantry mercenaries, and supplement them with your best warriors; don't forget to use javelins. Hopefully bless effects will make your sacred units a little better, so use them. Use overwhelming numbers. Make a sun priest your prophet, and smite away. Oh, and be prepared for heavy losses.

Strangely, you can afford to wait a little before building your blood machine : your national site gives you 3 blood slaves/turn, which is enough to keep your dominion alive. You are right, however, to start thinking about it from turn 1, because you will need it.