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Read trip reports at erowid.org and weigh the positives and negatives, most of the trip reports show how much was taken and by what method.
If you are still considering them I would recommend taking no more then 2 dried grams for a first try, you will definitely get a feel for them, and if you enjoy the company of your cousin then he/she would be a good guide for you.
I turned them down last weekend but was offered some yesterday, I couldn't not buy them when they were right in my face. I have done them multiple times in the past but the idea of a substance taking the steering wheel away from my mind has become less appealing but the trip can be very enjoyable...I haven't done these ones yet, maybe tonight!