Good thing its Adderall and not Ritalin I always called Adderall poor man E and Ritalin poor mans coke. Both are speedy and make you talkative, but Adderall has more euphoria and caused me less jitters. They both last a while, I found the Adderall to be nice and the Ritalin I just wanted to wear off.
Honestly I cannot help you with the dosing but I am pretty sure you can find those answers somewhere on the Interweb. I am guessing if its just one pill it won't kill you, but you might not want to take that much as it could be unenjoyable. IMO it is time released so just swallow it.
Here is something I found from a website:
"Adults
In adults with ADHD who are either starting treatment for the first time or switching from another medication, the recommended dose is 20 mg/day."
^That is for XR, so 30 mg is probably not too crazy of a dose. I guess you could break it and take 1/4's of the pill, or are those gel caps? I have seen friends crack open the gel caps and crush the little pellets to powder then enjoy nasally. Judging by my friends inability to shut up for the rest of the night I imagine it worked. You could do small doses that way, or just break it up and take small doses by mouth. I also just read that 20 mg XR is = 10 mg IR. So try breaking it up into 3rds, and go up as you feel necessary.
On snorting adderall:
http://www.bluelight.ru/vb/threads/69683-Snorted-adderall-30mg-burning-nose