I just copied and pasted this form the dosage section from AMT on erowid. Basically, all it says is that there isn't really a 100% safe way to find out what that perfect dose is for you. If you pop 30 mgs right off the bat, you might be extremely overwhelmed, or extremely underwhelmed, or it might be perfect !! You'll have to start low and work your way up if you want to find out what your perfect dose is. If you just jump in right at 30 or 40, you'll probably be okay, but it's kind of like playing russian roulette. anyways, here's what erowid says.
We have received several complaints by users that our oral dosages shown are far too low. There are a number of reports of individuals taking 100-200 mg recreationally and some of these people argue that the reports of overwhelming effects felt by others at 40-80 mg are exaggerated. It is important to keep in mind how much variation there is in experiential effects based on personal biochemistry, expectation, and other difficult to determine factors. We have received reports of overwhelming effects on as little as 40 mg and users taking as much as 400 mg (!).
We have also received several reports of severe vomiting, dissociation, dehydration, and extreme reactions with as little as 40 mg oral AMT. New users should not begin experimentation above the threshold level of any psychoactive drug and should slowly work their way up over the course of several sessions to avoid dangerously strong reactions.
People experienced in experimenting with powerful psychoactives recommend starting with very low doses and working up to check for one's personal thresholds for each compound.