I would help, but fluttering just confuses the heck out of me. I can't even imagine how to begin it, actually. =D So, don't worry, we're in the same boat.
(*everyone else groans in annoyance*)
I'm still amazed at how some people get soo good..
I keep watching that video of Sadie on youtube, i think you also posted it here. - i can't imagine myself ever getting it right..
Especially the flutter.. almost impossible.
By flutter you mean the fast movement of upper abdominal muscles? Well, the first thing is panting. Just try to breathe in and out as fast as you can while your upper stomach is moving. Then, try to continue the same thing, but without the air. For me it helps if I breathe in deep first and lift my chest a bit, this way it comes out best.