Making invisibility potion - what's the trick?

it isn't full stealth. armour you're wearing and whatever's in your hand still show, and mobs notice you up close, just from a shorter range. take the armour off if you actually want to sneak past something.

you can't brew it directly, you make night vision first and then corrupt it. water bottle + nether wart = awkward potion, add a golden carrot = night vision, then a fermented spider eye turns it into invisibility. redstone on top makes it last longer. don't forget the brewing stand needs blaze powder as fuel or nothing happens.