Anyone out there have difficulty with their technique? I have a problem with being too tight and stiff and this is really limiting my progress with both sound and speed. Any tricks for loosening up? I am currently working on Claire de Lune and trying to be "loose" is almost as difficult as learning the piece!

One of my exercises for relaxing is to let my hands dangle and drop them on the keyboard while playing C cadences. I consciously try to stay relaxed throughout.

You have to get into the habit of checking to see if you're relaxed. Otherwise, you're so concentrated on getting the finger and timing right that you don't notice that you're as tight as a stretched rubber band.

if you try to play a piece you are familiar with a few times using different touch - light(caress)/hard/staccato and even different rhythms deliberately, you might soon notice your hand/arm/finger tension would vary with different touch and speed. only when you find out yourself what make your tension/relexation occur with different touch, you know how to solve your problem. that's what i had tried.

An additional suggestion. Even if you consider it beyond your present technique level, try playing at least the first page of Chopin's Etude 25-1. I find it does wonders for me in loosening up the entire playing "apparatus," that is, elbows, shoulders, etc. It might not work for you, but it might at least be worth a try.