What's the best way to jailbreak iOS 6.1.3?

It's an iPhone 4. New to this jailbreaking thing and was wondering if anybody had any input.

Http://www.alphajailbreak.com/

don't plug it into your computer after you break it

It might be too late. I've been jailbreaking for at least two years now, and I've searched the web and the only things I've found are the ones that are a scam. The fact that it's an A4 is helpful, I have the same deal with my iPod Touch 4. Your best bet is to probably get back to 6.1.2 if you can and jailbreak it there.