+1 to what was said above :)

Hey but check this out, you can practice reducing finger tension even when you're not playing...

just hold your hand out, rest it on like an armchair or something so your hand is hanging down...

verrrrrry slowly, lift up ONE finger, and focus on not moving the other fingers... STOP if your other fingers move, and let them all relax...

keep doing that with all your fingers until they can move without the others moving them... :)

Another thing to do is to play guitar WITHOUT pressing on the strings at all! just either hover your fingers 2 millimeters away from the strings, and play like that (you'll notice just how amaingly relaxed your fingers will be)

and then you can also just play by resting your fingers on the strings and moving them about.... this will help a LOT!

implement and master!! :D