There's no sense in getting something that can kill you. There are lots of other more commonly available species that are just as interesting. I wouldn't recommend keeping a blue-ring until a person has lots of experience with non-deadly octopuses. No matter how careful a person is, unexpected things can happen. The tank will require maintenance, and unlike a lionfish, the octopus is going to be curious and it wouldn't be unlikely for it to quite literally jump on you. It only shows its beautiful rings when it's in attack or warning mode too.
For the sake of the animal, in case you do decide you just have to have it... it should have a 50 gallon or larger tank with heavy filtration, preferably with a relatively oversized skimmer. It needs an established, mature tank. None of that, "brand new setup just for the octopus!" business. They already had to cope with the stress of shipping all the way from the other side of the planet, don't need an unstable tank to live in. And it needs a locking, escape proof lid. The lock surves 2 purposes. It keeps the lid secure and the octopus in the tank, and it keeps the lid secure, reminding you not to just stick your hand in and grab it or detering an ignorant guest from "playing". Sparing you the lawsuit that would ensue briefly following the untimely death of a visitor/child.
