There are many samples online regarding privacy policies and how to word them. It's a good idea to read over several different options and adapt these to suit your particular niche website or blog.
Privacy laws differ in different countries, so you'll want to be fully compliant wherever your planning to market your website or blog. Focus on what you'll be using the data that is collected for and how it may or may not impact your website or blog visitors.
You'll also need to give your users a way to opt out of this so that if they no longer want to give out their information, they don't have to.