Find a corridor or two trees that are close enough that you cannot turn on the spot with both hands to the sides without bumping them and place your back on one side of the wall. Place one CLEAN leg on the other side. Find the support with your back and lift the other leg. Play with your back to find the easier point of support and use the hands and legs to move either up and down or to the sides as you keep yourself off the ground and learn to create support for yourself.
This is a fun drill for kids as well and can be usuful in gaining a different perspective or if you need to reach something higher or over rough surfaces. Work on this to free your movement and you can also do this using a door and climb over it. This too is a way to look and hide or get to a hiding spot which requires nothing but you and some breathing.
Tension is not a dirty word. It is one of the tools you are born with. Just use it and avoid trying to become something not natural. If you are tense, breathe and it will come out in a natural way. Forcing relaxation simply pushes it under the carpet and it will come out in another way.