Recommendations on Upgrade path for Directoy Press 6.3 to Latest update

We are about to upgrade to the latest directory theme and WordPress

Currently we have WordPress 3.8.x and Directory press 6.3

What do you recommend the path to get to the latest and do any of you know some hiccups to look out for as I go through it.

I do have a place to test my upgrade but I was wondering how has everyone’s experience been with this. We have some active listings and we have customized some of the pages. Nothing major because it looks like the new theme actually has the customization we did.

Any advice out there? Do I upgrade wordpress then the theme or vice versa? Do I step the Directory press to various versions or can I go directly into the new one. I know my layout I will have to rebuilt but how about the listings and the database schema for those listings… was wondering if I would have issues with that?

THANK YOU IN ADVANCE