Here's a very detailed description of how to stir fry greens:
I use fresh garlic cloves. It works well in a large saute pan or dutch oven if you don't have a wok. I wouldn't steam the vegetables first, but I'd cut up stems into smaller pieces - say one inch (usually on the diagonal) - and the leaves into three inch pieces.
Oh - for the shrimp - you don't need to steam them either - maybe stir fry them first, remove, then do the greens, then toss the shrimp in again at the end.