Lark's head
The one knot that matters most. Attaches line to kite; tied wrong, it unties itself at the worst moment by design.
Bowline
The loop that never slips. Every line end on the ground should carry one, and every flyer should tie theirs in the dark.
Sheet bend
For joining two lines of different weight, as when the training line splices onto the real one.
Clove hitch
Anchors a line to a spar. Fast to tie, honest to untie after a day of load.
Rolling hitch
Takes load off a strained section while you repair it. The repair bench ties forty a season.
Figure-eight
The stopper that says 'no further'. Goes at every line end that hasn't earned a bowline.