Oh Datura....

As far as my experience goes, I have had an ayahuasca brew with a 'cousin' plant of datura (something very similar, I don't remember the name) as well as a fair amount of tobacco tea in it, and oh boy was it an UNCOMFORTABLE night.  A good indication of it is that your whole face, mouth, and other extremities will go completely numb rather quickly.  A good thing to remember about Datura, well probably the MOST IMPORTANT thing to remember about it is that it is a very strong plant spirit and likes some people and doesn't get along as well with others.  Some people naturally find that this plant is very kind to them and has amazing experiences with it.  In this case Datura is an ally of that person.  If you have an uncomfortable experience with it, I would recommend NOT trying again because it more than likely will just get worse or potentially lethal. 

The book "A Seperate Reality"  (Carlos Castenada) goes in depth with this relationship between strong plant spirits and 'men of knowledge'  and I would highly recommend reading it if you haven't! 

(I think its in a Seperate Reality but I have read many of these books and I apologize if I may have gotten them mixed up.)

Also, large amounts of Datura can EASILY make someone go crazy....for good. 

Personally, I would sit and meditate with the leaves/seeds in your hands or resting on your body and reverently ask the plant if you can ingest it and when...

I hope this helps a bit!

Safe travels and many blessings on your adventures!

~starseed