Knots

Five knots is enough

You don't need a hundred knots. You need five you can tie in the dark with cold hands.

The five

bowline    a loop that never slips
taut-line   adjustable, for a ridgeline
clove hitch  to a post or tree
figure-8   the knot that comes undone
trucker's   tension for a load or tarp

Practice

Tie them blindfolded. Then tie them again when you actually need them — that's the only test that counts.