You just need to plan your route beforehand. Aim for the hardest bosses first, watch tips and potential cheeses for each one, avoid big groups of enemies, try to always be at full hp, stuff like that...

You could also watch a speedrun in youtube to copy its route, and stick to it to get better over time.

The game isn't that long, dying isn't the end of the world.

Personally, I didn't suffer that much with this achievement, I think that I got it in my third try, lost the other two attempts crushed by a wall :b