SimpleumCheck has created a database of recommended settings to increase security on a Mac. They have broken things down into three categories: Basic, Professional, and Paranoid. Each category has around 20 checks that are broken down into high, medium, or low risk as well as showing which checks that your system passed. That is a lot of info, but if you want to simply focus on the high risk items then you can get some good things done in the first ten minutes of using the app.