How do you negotiate for an offer?

My last working day is 31st March and I received an offer today. They are giving the salary I had asked for, I think I just asked too low. I come from a tier-1 college and since my previous salary wasn't very high I didn't ask for much.

As I hadn't had any offer in hand, I didn't negotiate further. Though for the future how can I negotiate?

Thanks, butterbean