The best option is to choose the very light difficulty and Death by Chapter. There will be more resources, the enemies will be easy to defeat and there will be less of them, and you will receive irrelevant damage. However, always let a medical kit ready and try to be always with max health for not getting lethal bites from stronger infected. Watch out for the falls. If you do this after beating the game and after doing some upgrades this will be even easier.
*** Spoiler - click to reveal ***The worst part for me was in the act Seattle, Day 2, at the chapter The shortcut, when Abby has to climb up a skycraper and pass through thin wodden bridges. If you fall down, you'll have to waste more 40 min to do everything again. According to other guides, you must stop walking when the joystick starts to vibrate. And try to control the balance doing left and right with L3, as the game says. Good luck at there.