Personally I've been surprised how well setting up contexts for intended outcomes ahead of time works - e.g. if I want to study X, I close everything else on my computer the night before and only open the textbook and my reading notes; If I want to get up on time and go for a run I put my running gear in one place all ready to put on, etc. More generally I try to prepare a daily note on my computer the night before with the most important few things I'd like to focus on.

But what works and doesn't it's highly personal, e.g. the hosts file thing has never lasted more than a day or two for me :)