[aout]

Don't learn anything specific but be sure to be ready to learn everything when needed. I had to learn linear algebra when I was a 3D engine developer, then I had to learn statistics (or maybe learn to understand the notations of it so I could use scientific papers in my work).

In the end I think it was best not to have lost hours, days, weeks of my time on things I "could have used". I find it best to be prepared to learn anything.