I block all websites, and the ability to install new apps.
What I do, is let someone close to me make the parental controls code, so that if I need some configuration done, it's never too far away.
And after this initial setup, whitelist as needed.
I know it severely limits the browsing capability as basically you can't use the browser freely, and I know it might not be for everyone, but I find that for the time being it works for me.
Yes, it's scary to give up browser capability, but it basically gives you a ton of control back in living your life normally.
Hope this helps.