First, death penalty. If you take a life and there is overwhelming evidence - not just beyond doubt - that you did it, you will die, that week, by hanging.
Second, change the prison system to make it a place of therapy, education and corrections for the first offense. Helping people talk about why they commit their crime, and how they can re-enter society and not offend again.
But for the second offense, a hideous screaming nightmare world from which there is no waking, where a man is constantly bombarded by his darkest shadows and sent to the point of clinical insanity. I wouldn't even feed them real food - just dump a truck of scraps in the courtyard every second evening. Whatever happens, happens. Cells that are totally bare, and through the night have zero light or sound. Fights between inmates not broken up. Real "How could you do this to a human being?" shit. Rapists especially, generally lose their rights as people, given generally a cell as a bare concrete room with a stool and noose already set up, and are fed and tended to 'when we get around to it'.
I call it the 'You Had Your Chance' system.
I'd have to do a lot to ensure fair trials and uncorrupted police, but I'm sure I could make it work and horrify some other countries with my soulless brutality.
But outside the scum of society, I would be a benevolent leader, ensuring as many of my people are as happy as possible. Total legalization of gay marriage - not civil fucking unions, MARRIAGE. Gay people have as much right to be miserable as anyone else.
Welfare for the truly deserving - sometimes shit happens and you can't survive on your own for a little while. Pour as much money as I can into education so people CAN better themselves, along with hospitals and clinics, ensuring people can always get the treatment they need.
I want my people to be as safe and happy as possible, and I believe the key to this is rehabilitating, or torturing those who would threaten it.