This is not the first Wordpress site i have ever run but it

This is not the first Wordpress site i have ever run but it is however the first one that i want to give a feel of quality, professional and serious at the same time. My main concern is security without to much restriction to a user or guests visit.

The site will be a more or less a hobby site and be a place to visit for a few laughs with a main focus on images and posts. So i think while i will need a friendly way to show galleries without having to keep hitting arrows and changing pages. That annoys me so a lightbox or similar modal gallery would be awesome. But i want users to feel safe registering.

What considerations and steps should i take or can i take to ensure the site is as secure as it can be ?

Also any ideas on ways to show galleries as described above are welcomed.