How to Clean a Lobster Tail for Freezing or Cooking
Kill the lobster by pushing a
knife blade into the body
between the horns
Next remove the tail by grabbing the body in
one hand and the tail in the other.
Twist and pull firmly.
Next remove an antenna to clean out the vein (aka poop shoot).
Break off the tip of the antenna.
After lobstering, I immediately clean the tails on
the beach and put them in a zip lock bag.  
Uncooked I put the baggie in the fridge or freezer
to be cooked at a later time.  Frozen, the tails will
last an easy 3-4 weeks.  
Insert the antenna into the anus hole and twist 1/2 turn.
Pull the vein out, it should look like this.
That's it, rinse in salt or fresh water and your ready to
cook or freeze the tail for later.