You want it dry.
I bought a bunch of 80 micron screen awhile back from someplace online. That's the size I use.
Get two buckets. I got two 3 gallon at Lowes. Cut the bottom out of one and rig your screen up over the hole. I just taped mine on real good. I use dried weed that I put in the freezer before I use it. Put the weed in the top bucket, add dry ice on top and let it set for a little bit. Then shake for about ten seconds. Don't over load the bucket. The first shake is all I keep. I'll shake again and give that to a friend. It's got some green by then but they don't care. Easiest way to do it. Only takes a couple minutes and is ready to smoke immediately.