Welcome to the forum! Great intro. 
Generally, when talking about gods you contact them by name. An image you (she) likes for the entity helps, and for these, as it’s a dead religion she’d have to build her own relationship from scratch. I don’t know if there any revivalist Aztec groups around like there are for the Norse and Druid religions, but it’s a broken tradition and in any case some of it would be reinvented by modern occultists and subject to speculation. So she would have to make it up for herself, really.
Here is a getting started with magick guide.
We have ideas on getting your spiritual hygiene sorted out, and working on developing your astral senses that you might like.
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