If this is your first time ever using a prescription stimulant, I would not recommend 30mg insufflated at once, but rather two 15mg lines. Get a feel off of 15mg (Which should give you an effect if you have never used before) and if you feel like you want more, you can finish it up.
Expect to feel speedy, focused and euphoric. My first time snorting Methylphenidate, and many times after, I was extremely euphoric and thoroughly enjoyed it with little side effects. But, you should expect a comedown after around 2-3 hours after your last dose, which will leave you feeling lower then you were before and possibly sick.
Stay safe and don't make a habit out of it ; )