We have 8 kids (12 - 23) and homeschool.
Dansguardian is the best tool I have used so far.
We have been using it since at least 2007.
Just need a pc with 2 nic cards.
It lets you score specific words so that when someone goes to a web page, if the score adds up to your preset limit, they get a blocked page instead.
I am quick to open up pages whenever someone asks to be able to go to a page.
My wife and I are not usually hindered by the filter.
Adding the dns would be a good idea and I have not done that yet.
Also, while none of my kids have a smart phone with a plan, they do have smart phones they have purchased on ebay and use it as a wifi only device.
That means that anything in the appstore is fair game.
And Dansguardian does not process that.
It only processes port 80 traffic.
So while you can "keep and honest man honest", it is still necessary to teach them that bad stuff is bad and why.
I am so glad the internet was not around when I was a kid.
Curious and liking girls are two things the internet is glad to fulfill.