Step 1- Collect extra wisps every night instead of sleeping
Step 2- Go collect some Yigg Branches
Step 3- Place very cheap wisp torches (1-1) everywhere

Bonus: Put away your Wisp Light, it's like ringing a dinner bell (specially to Gjall) no matter how good your sneak is (And if you're sprinting and jumping even worse). Just use Torches until you get to the new bench/sword. It'll make you create a network of clear land/blue lights you can see through the mist, which you will want later. If any torches are broken, enemies are near, kill them and put them back up.

Have fun out there!