Boy Scout knots...
...do it for me. The square (reef) knot, bowline, 2 half-hitches, clove hitch, sheet bend, timber hitch, and tautline hitch are the basic first knots taught Boy Scouts. Add the marlinspike hitch, bowline on a bight, water knot, prusik, fisherman's knot (anchor hitch), cow hitch (lark's head), figure 8, and a few others picked up along the way, and you can pretty well tie up anything you want. In sailing, I use the reef, bowline, clove hitch, and sheetbend most often. Forty years of scouting, as a boy and an adult leader, allow me to use knots pretty well. I am amazed at the number of people who cannot tie any kind of useful knot, and can't untie whatever they do tie...

-Paul