For eye strain specifically - f.lux on all computers, Night Shift on my iPhone, and anti-glare coated glasses. Combine that with getting up every 20 minutes to walk for a few minutes.

Additionally, I use some good quality eye drops like Systane Balance which help lubricate my eyes when I wake up and before bed.

A new thing I've been trying to do for multiple reasons is write out my designs on pen/paper before sitting down at the computer. This has helped with eye strain and also helped me better clarify my ideas instead of sitting at my computer and "wandering" through the problem space in my IDE.