Knots are easier to teach in person than via the Internet.  But if you want to do your own research, here's our recommendations.  (We teach these knots for outdoor education groups and community events, sometimes in pirate costume.)  

There are many good knot books and websites.  We particularly like Hervey Garrett Smith's books (The Arts of the Sailor, The Marlinspike Sailor) for excellent, clear illustrations.

Good Knots to Know:

The best knots tend to be stable under load, easy to untie when slack, and leave the line undamaged (so it can be used again and again).  

• Fixed loop: Bowline
• Stopper-knot (the end of a line): Figure-Eight
• Bend (two lines end-to-end): Carrick's Bend or Sheet Bend
• Hitch (a line to a pole): Half-hitch, Clove or Diamond hitch
• Decorative knots: Square Knot (Boy Scout bandanas) or a Sennet or Turk's Head

and two of our personal favorites, for practical amazement: 

• Erica's Cowgirl Teacher's Admiral Neighbor's Un-Tie-able Double Bow Knot, an improved, reliable and quick-release knot for shoelaces (replaces "double-knot"), and 
• Ernie's Almost Famous Re-Usable Trucker's Hitch,  It's handy for securing loads onto trucks, boats, or packs; cinching down loose material; or tight and trim rain-fly tarps.  Especially if you have only one rope to serve all these purposes on a camping trip.

Ernie's #1 trick to learning any knot: practice. It's your hands that learn it, not your head.  Start with one or two useful knots; practice them a lot.  Once you've mastered those, move on and add more.

What Erica looks for in knots:   "Over-Under-Over" (like Celtic knot art), and "Looping Through." Over-under-over tends to secure a knot, most reliable knots have this pattern somewhere in them.  Looping through can turn a secure knot into a removable slip-knot, which can be temporarily secured with a half-hitch. 

Remember, the best knots are generally stable under load, easy to untie when slack, and leave the line undamaged (so it can be used again and again).  Deliberate exceptions are few: for standing deck gear, you may occasionally create a truly permanent knot that will be worn away in place, and needs to be smaller than its removable counterpart.  You may learn some 'trick' knots that release under heavy load for fun or safety (e.g. panicking horses, or Indiana-jones-type bullwhip ladders).

Avoid knots that tend to slip or jam, and that weaken the rope by pinching or kinking. Examples of poor but popular knots include the Granny Knot (really an open twining) and the Overhand Knot.  Even the Square or Reef Knot tends to slip, jam, and bind, and is not suitable for many purposes. These are dangerous, annoying, and unsightly knots; you can't trust them, or the rope they've corrupted.  A Figure Eight or Bend will replace these knots most of the time.

  When we teach a 1-hour workshop, we bring lots of examples for people to play with, but we focus on just 3-4 knots.  We teach and practice these until everyone "gets" at least two knots that they can take home and practice.   We adjust to the group's interests and experience.

Past knot workshops and activities have included adult presentations like Cascadia Wild's "Practical Knots for Impractical Situations," sailmaking, rigging, and kayak-lashing, and the marvelously named TrackersNW Summer Camp, "Revenge of the Kung Fu Master Nature Viking River Pirates."

Pirate-themed booths for community festivals are also popular.

Examples of Ernie's personal knotwork:

-A decorative dragonfly Ernie tied, off-handedly, for a Web discussion:

Rigging (grommeting) in progress on the Anaiis;

- A ridiculously large cedar beam ("boat parts") on a ridiculously small Geo Metro: 
Ernie knows it's lashed down when he can hoist the cargo and lift the car. Load limit on the roof rack, 175 lbs.

Coming Soon: Sailor Christmas Presents: including a very pretty, and time-consuming, personalized Rigger's Bucket.