I have been working on these to tricks for quite a while now, and today, I can finally do both. (not perfectly, but proficiently) so i thought I would right a brief essay on some tips that helped me since all the mistakes I had been making are still fresh in my head.

I will start with mills mess. Mills mess is broken down into like 12+ steps when you are learning. Its over whelming. I got to the point where I could do one throw and catch of each ball from both sides, but not continuously. I could only get three throws in, and then the pattern would fall apart. Well, it just so happened that as I was taking a break from mills mess, i was messing around doing things I could do. One of the tricks that came up was the windmill. If you are not familiar with it, I am sure you can youtube it and find it easily. As I started switched directions, I noticed that i felt like mills mess. I then remembered hearing something long ago along the lines of it you switch the direction every three throws, its the mills mess. Sure enough it is! So rather than learning all twelve steps, I highly recommend you learn the windmill going both directions and it it will make learning mills mess so much easier. Keep in mind though that still want to exaggerate the motion of crossing and uncrossing your arms. It looks much better.

The full shower. Oh how this trick gave me grief. It messed with my mind to no avail. I swore off this trick around 7 times...but i kept coming back. so here is what helped me.
-I had to (and still do--remember, i just got it today) really focus on throwing two balls out of the same hand to start the pattern. It went against all my "training." So remember the first two balls are out of your right--or left--hand.
-secondly, i never quite new when to throw each ball. I was never taught this trick, it was something that seemed straight forward enough; I just went for it. I had always tried feeding(the quick throw from hand to hand) the ball when the first ball was at the top of its arc. As it turns out, that is when you throw the second ball. You don't feed the ball until the first ball is almost half way down. You are almost catching your fed ball and thrown ball simultaneously. You catch the fed ball a fraction of a second sooner.
-learn with bean bags!!!

Hope this helped...if there is an unclear part, let me know and i will try and expound.

You should post some video.

OK, I will make a video when i have some time!

Very nice!