I generally don't bring it up. Like others have said, if the topic comes up I'll speak openly about it. I don't try to hide it, but I don't throw it around either. I actually just had an argument at work about it with some ignorant religious dude who claimed we live in a Christian hating society, and that Obama is a Muslim simply because of his name. Also claimed that Tim Tebow is being kept out of the NFL because he's a Christian.
What actually lead to me being a more open Atheist was Facebook. I had tons of people posting religious pictures, bible verses, asking for prayers, etc. So I started posting Atheism pictures, quotes, etc. on my page and kept track of how many people unfriended me or sent me messages to knock it off. Looking for those pictures and quotes to put up really opened my eyes to what I actually thought, and made me angry that I felt like I needed to hide my lack of faith in god from my family and friends.
What actually lead to me being a more open Atheist was Facebook. I had tons of people posting religious pictures, bible verses, asking for prayers, etc. So I started posting Atheism pictures, quotes, etc. on my page and kept track of how many people unfriended me or sent me messages to knock it off. Looking for those pictures and quotes to put up really opened my eyes to what I actually thought, and made me angry that I felt like I needed to hide my lack of faith in god from my family and friends.