Tony gave you a good advice. First, last month's rent and security deposit is quite standard in my area. But more and more tenats cannot afford to pay all 3 up front. So landlords end up accepting only first month's rent and security deposit or all 3 but last month's rent to be paid in few installments until paid in full.
It is not uncommen for the security deposit to be equal to a month's rent, and you can ask for whatever terms you are comfortable with. You may want to check and see what is customary for your area, because asking for to much could certainly hinder your efforts to get it rented.