there's beta readers and groups that meet and groups online. There are, more importantly, groups that are too soft and inoffensive, vs. groups that take pride in eviscerating the victims, which call for a good moderator. Of course, then there's the question of getting one. One model is that everyone gets a turn to speak about a story, the writer last, and then you get a free-for-all.
If all the readers think there's a problem with something, there's a problem. Of course, they may be entirely wrong about what the problem is.
The delicate art of filtering one's criticism, because either changing to meet all expectations or rejecting it all is pointless. (It's also impossible to meet them all, because they can contradict each other.)
Focus on the big picture -- plot, characters, etc. The little phrasing problems will be swept away in the fixing of those, if replaced by new ones. (I didn't get a chance to observe that if it's a systemic problem, like wordiness or dangling participles, that can help. But certainly sentence-level problems aren't so big as the higher-level ones.)
Putting stuff aside before revising and then submitting it to readers.
One question was about how to cope with rage, despair, and only then getting down to tackling the crits. Answers were: you're doing fine as long as you do tackle them; make sure you don't abuse the readers, and take notes.