Security Deposit Amounts? Last Month's Rent?

[Art Maydan]

I'm getting ready to rent my first unit in the duplex I just bought. I can't decide what to charge for the security deposit and whether or not to ask for the last month's rent up front. I don't want to scare people away with too much up front cost, but I also want to protect myself. 

On the high end, I'd charge first and last month's rent up front and 1.5X rent for security deposit. What do you think?

Much appreciated!