1) Everyone should write tutorials for newbies and give them out for free for newbies, that will teach them how to start out in bitcoin, and what risks they need to consider. Highlighting important topics like backing up wallets, and passwords, and also keeping their systems safe from malware.
Not everyone can give good/simple tutorial for newbie, so i think everyone who can't make good tutorial should use good tutorial from other people.
2) Every wallet software should integrate a warning window warning users to backup their wallets and passwords before creating the wallet. The warning should be in big red letters , so that newbies can see it, and this might make them realize that it is important for example:
WARNING!! BACKUP YOUR WALLET/SEED/PASSWORD OTHERWISE YOU COULD LOSE ACCESS TO YOUR BITCOINS
Not only warning window which only show once, maybe also show the warning every days/weeks.
3) A pinned thread on the Beginners & Help section warning users to backup their wallets & passwords
Might be good idea, but as far as i know, most newbie that i see never see pinned thread.
4) Bitcoin.org and wallet websites should also tell newbies to backup their stuff.
I think bitcoin.org and wallet's website already tell newbies about it.
Maybe make the info bigger or put it at homescreen to get their attention.