Is it OK to repeat the iPhone 4 jail break / unlocking procedure?

I recently went through the jail breaking tutorial to unlock my Iphone 4 GSM. It seemed to go OK and I didn't have any problems, but after activating my sim on the network that I'm switching to I am still not receiving any signal. My question is, could I go through that tutorial again and make sure I do the steps again without causing any damage to my phone? I used the following guide: http://www.iclarified.com/29761/how-to-jailbreak-your-iphone-4-using-redsn0w-mac-613 Thanks.