Check this topic my Maya, you will find lot’s of useful information and variety of builds.
The Carnival - A Guide to Pets - Grim Dawn / Classes, Skills and Builds - Crate Entertainment Forum
As for what to focus depend on what kind of gear you possess. If you have Beastcaller set focus on Bria, while Bysmiel Trinkets will help you create Bird(s) build.
For end game version you can check Fwuffy Squishy build. Or check leveling guide for Conjurer class.