http://youtu.be/1aGh834LqFs
http://youtu.be/gDYmWbRRymM
http://youtu.be/9GK70mzNZyg
The stick does 80% of the work, the bucket & boom movement is minimal to keep the stick moving. The bucket is about 10 - 20 degrees tilted down from level as you fill it. Don't try to hog it all in one scoop, another words don't over crowd & pull debris into the tracks.
Something that stuck with me from early on, a 30yr vet said to me, how to spot a good operator in an instant is watching how much their tracks move while they're digging, getting maximum digging force from their machine without lifting or sliding the tracks on the ground.
What I did early on was get two shoes boxes, filled one with durum wheat & transfered the grain back & forth... the grain had little resistance for the bucket to glide through, a bit of sideways give if I swung by mistake, but still had some mass to it similar to dirt... I perfected my technique before digging dirt, which is much less forgiving. Rice might be more readily available to you, just quite a bit lighter.