The main part of the system is the rim tape, it needs to be airtight and sturdy enough not to tear once air pressure forces it into the spoke holes. Stans is pretty expensive, so I use Joes but it’s more or less the same. I’ve also used BMX tubes too with varying degrees of success.
Now, if you’re planning on just using rim tape or gorilla tape, then you need to punch a hole for the valve in the rim’s valve hole and fit one of those Superstar jobbies. The will seal once you tighten the locking collar. Replaceable cores are a must, but they will also be a pain in the tits as they need to be tight enough not to loosen when simply trying to attach a pump…
719s are as good as anything – in fact it’s what I use for my tubeless bikes. Sealants can vary, but I’m hugely impressed with Caffelatex.
As for tyres, some are good and some aren’t. Folding Continentals are a pain, they leak from mould holes. Kendas work well, although the sidewalls are weak. I’m using Specialized Captain and Storm tyres on my xc bike, which are excellent, they’re designed to be used tubeless.
You also need a reasonably decent compressor too, obviously.