How do you level up the fastest?

I remember when I was a 10-15 year old kid. I could play my NES or SNES literally all my hours awake with only 2-3 breaks for food so I guess its the same with kids/adults with no jobs nowadays =) And as you said yourself; its survival time that gives the most XP by far (lalmost 200 xp per minute compared to 50 xp per kill) so I guess playing safe and avoid fights is the way to go if you wanna level up fast.