One more thing to note about caching, if you have any dynamics in your shot, be sure to go ahead and either bake out the simulations, or setup particle caches for your particle sims as that makes things TONs faster.
Plus, doing that also allows you to render particle simulations on multiple machines or a farm making sure your particles all look the same in the final render
Good luck!
PS, when you start rendering shots at 4k, and your rendertimes on the farm get to be around 4+ hours per frame, THEN welcome to the club
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com