Practiced my open guard quite a bit on all sorts of body types and experience levels. The more I practice my sweeps, the more I start to see then whole point of the art, and I am blown away. I have read about it, or heard about it; jiu-jitsu is a game of leverage and timing (as well as balance, strength, flexibility, power0 , but I think nowhere else do you see this more than in sweeps. The human body seems to generate excellent points for leverage, which actually are dependent on the position it takes. The funny thing is that you always have a direction where you have no base. Take the base away from your opponent, apply the technique when his weight is at the right spot, and boom, you're on top, regardless of how much said person weighs. It's absolutely amazing.
I want to get in competition mode, and to do that, I am focusing on sharpening whatever tools I already have in my repertoire, and I try chaining them as much as I can. However, there's a very fine balance between wanting to impose your own game on your opponent (and missing nice opportunities for sweeps/submissions) and listening to your opponent's movements and capitalize on them. This distinction is still pretty much unclear to me, however I do seem to do a whole lot better when I piggyback on whatever move the person is doing. Actually, my worst rolls come when people are extremely conservative and avoid exposing any sort of limb (for example grabbing my gi pants at the knees and just staying there). I really have a hard time with that sort of game. My best sweeps are those when someone stands up after I've tried sweeping them from the knees. My most favorite sweeps come when the person leans their weight into me in some way or another.
All in all, I've got a lot of thinking and rolling to do in order to become a competitive player.