This document is not the common step-by-step guide on how to protect your wordpress installation. A lot of sites cover that already, so I will talk about some additional topics that you don’t see around very often, specially torwards security with obscurity.
I am not propagating that just by hiding the version of wordpress is going to make you more secure, but the truth is, why SHOULD ANYONE know that? No user of your site needs to know your wordpress version or Apache or PHP version. Good security practices always specify that the minimum privilege (or information) that you give, the better.