I've been making Machinima films using game engines for the past 20 years or so, including working with people like EA, the BBC, et al.
(I'm actually the guy who coined the word "Machinima", with a colleague, because we needed a better way to describe what we did than "Quake Movie".)
So I had a lot of game engine experience before I jumped in.
As for beginners getting started: Unity, Unity, Unity. Grab Unity and start learning - you can get a simple VR experience going in a fairly minimal timeframe.
Do you mostly use Blender to create the actual environments? I've started to do a little reading on this stuff too and it's a daunting hill to climb coming from primary a web-dev background (at least I know C# like the back of my Left Hand haha couldn't resist...).
I'm mostly using the Unity level editor, in actual fact, although I use 3D Studio Max for my detailed 3D modeling when I need to.
The Unity editor's very powerful, and you can extend it with tools like ProBuilder and Gaia, which are all available in the Unity Asset Store.
(I heartily recommend both of those for simple geometry creation and landscape creation, respectively.)
I've been coming at it the other way - I know game engine graphics and assembly like the back of my sinister hand, but I've been on a rapid C# learning curve :)
Just wondering what tools or techniques should you specifically learn to make VR games in Unity? I can make desktop games in Unity, is a VR game just like a FPS with different physical controls?
(I'm actually the guy who coined the word "Machinima", with a colleague, because we needed a better way to describe what we did than "Quake Movie".)
So I had a lot of game engine experience before I jumped in.
As for beginners getting started: Unity, Unity, Unity. Grab Unity and start learning - you can get a simple VR experience going in a fairly minimal timeframe.