I'd say as an eventual goal, make a base on a decently sized island. Make the eventual goal purifying the island and keeping the taint away permanently.Rush Ars Magica for a dig spell mixing Touch ,Projectile, & Dig. Level up some and grab mine power & area-effect. That gives you a distance shooting area effect dig spell. In Thaumcraft rush the Arcane Bore & ethereal bloom. Scan all nodes you find, if they are tainted break them. Find a portal to Twilight forest and mine there. Swim far out to ocean and build there. Break crusted taint, dry up the liquid taint(if you cant throw a block on it break blocks beside to thin it enough or use water bucket), water bucket fibrous taint for quick breaking. use ladders, walls(wall blocks not a wall built with blocks) & torches to stop taint spread.
It will be a losing battle, Taint spreads far to quickly to keep it gone for good but you can keep a base area clear, Build your mine entrance on a pure node area, build the entrance to your base platform above it to keep your camp clear. Raid everything for building materials artifact towers, ruins, walled villages are all resources that can be yours with a pickaxe and a will and once you have a dig spell you don't need an axe, pick, or shovel to get materials. The spell can get it all. Soulbound enchant your spellbook. Nothing worse then dying and not being able to do anything till you get your corpse. And sneak near hungry nodes it lets you get closer before being dragged in & drop water if you can so it softens the landings.