please read directions. Don't listen to people telling you to press the water out. Squeezing/Pressing the water out of your wet bubble hash will force water into the trich heads, and most likely will mold. Don't roll your bubble into balls either, same thing will happen. The extra square screens are for drying, just use the right ones so the bubble doesn't fall through. You must take all precautions to allow the bubble to dry completely. People always fuck that up, and create/smoke moldy hash without knowing it, because high times magazine shows giants bricks of hash surrounded by dozens of balls of hash. Don't be a statistic.
What bags you need will vary between strains. There's alot of variables, but generally when the bud was harvested in terms of trich development will dictate what bag works best. You won't know till you try. I typically use all the bags, as this will help seperate the different grades, and prevent shitty green leaf getting into your full melt. At least start with all the bags, till you figure out what your getting from them, then re-acess which bags your using.
Btw. don't mix inside your bags. that will just beat your bags up, puncture them, cause them to peel, and eventually wear holes. You can do all your mixing in a food grade plastic bucket, then pour into another food grade plastic bucket that has your bags in it. This also prevents pushing things through the bags when mixing. Sometimes I run stuff twice. The first time I give it a gentle mix, hand stirred with big stainless steel mixing spoon. The second go around, I mix with a similar spoon attached to my drill, I'll hit that pretty hard sometimes depending on what I got from the first round.
I say food grade plastic bucket, cause any stupid orange home depot bucket will introduce plastics into your bubble
seriously, just don't use them!!!
Freezing your trim 24 hours prior helps, and If you really want some amazing bubble, look into water curing before you bubble. That way your pulling all the nasty stuff out of the leaf before you start extracting trichs. IMO, it's a bigger pain, but really makes for some great bubble.