Hi Mystical and welcome to the forum.
I'm not real good w/practical knots, but according to the link, the US Department of Defense and US Customs and Border Protection use these.
http://www.netknots.com/html/pko.htmlOutdoor Knots17 essential knots cover most any rope tying situation: Bowline, Square Knot, Water Knot Rolling Hitch, Sheet Bend (Doubled Sheet Bend too), Trucker's Hitch, Mooring Hitch, Tautline Hitch, Clove Hitch, Buntline Hitch, Constrictor Knot, Double Fisherman's, Figure Eight Follow Through, Prusik, Butterfly Knot, Half Hitch and the Bowline on a Bight.
Paddling Knotshttp://www.netknots.com/html/pkp.html14 essential knots cover most any rope tying situation: Bowline, Square Knot, Water Knot, Rolling Hitch, Sheet Bend (Doubled Sheet Bend too), Trucker's Hitch, Mooring Hitch, Tautline Hitch, Clove Hitch, Buntline Hitch, Constrictor Knot, Double Fisherman's, Figure Eight Follow Through, Prusik, Butterfly Knot, Half Hitch and the Bowline on a Bight.
Here's the Complete Guide to Knots (donate a car too!). The cards above came from looking around on this link.
http://www.actiondonation.org/articles/complete-guide-to-knots.html