Before I start I want to say that I did read the similar post on this page. However, I had some other questions that may not have been related to that post so I didn't want to hijack it.

I'm going for Dragoon so I am curious, can I continue doing my story as a Lancer or do I need to stop now for DRG?

I know I can get skills from Archer, Pugilist, and Marauder but how far do I need to take each class? Should I get all my cross class skills possible before switching back over to my Lancer/Dragoon?