I was asked at writing group how I handled plot critique and if I made suggestions about the directions people’s stories should take.
Plots are a tricky one as this is the part based on your idea and therefore I never want to hijack anyone’s idea.
I analyse plots carefully, often providing a story arc if I feel the who/where/when aspects and the question driving the novel or short story has not been focused enough. Perhaps the shape is off, perhaps some areas don’t build the tension enough or the subplots aren’t integral enough to the main thread. Perhaps the middle loses direction or the ending fails to resolve the burning question of the story.
So I look at key plot points and ask the pertinent questions, I also look at character change as a function of plot and at motivation for action.
I only suggest actual plot ideas or make suggestions about how something might be changed if I can see the fix and even then I tend to point out it’s Debz the writer and therefore more subjective when I make suggestions. Usually it’s highlighting an area of weakness and the hope is they come up with a third better alternative.
That is all!