The basics to be safe and secure on blogs are to always make sure no one knows your password. Services like Google and Blogspot have immense security so if you get hacked it more-than-likely wont be their fault, it will be something you've done on the computer such as downloaded a virus. There are viruses what are called keyloggers where they record everything you type and send back that information to a person. Another thing to be super secure about making sure no one gains access to your account is to make sure no one is watching what you type when you type.
You should always be extremely careful about posting personal information such as if you are leaving your houses for a couple of days or something. Because if you do some thieves might take a keen eye to your house. Also it's the same principle when it comes to telling people what you have recently bought such as a Brand New 3D T.V worth like £2,000, there are people in the world who wont think twice about taking your valuable possessions. You should also never include your phone number in anything as people will ring you up about advertisements or you may even get abuse if someone dislikes what you are posting.