Thinking back to when I did Lit, this post resonates with me so much!
With Lit you are given so much freedom of expression and leeway in terms of structure. While I found this made the subject more engaging and interesting it occasionally also made me very lost.
I think sometimes the best way to get around this is would be when doing, say, a passage analysis, to go through the text line-by-line. That way you have a clear goal in mind — methodically explaining how the author is conveying meaning. This is a great way to tackle practise SAC's and build your confidence; and I agree with MightyBeh, Lit requires a lot of practise to refine your technique.
You'll find that when you start analysing the passage line-by-line, the further you go with your analysis, the more connections you'll see between the passages and thus your response will naturally gain in complexity without having to even think about it. Another thing I always did when I got stuck was to re-read the passages three times: once for context, once for the themes and once to see the connections between those themes and the specific language techniques used by the author.
But ultimately I think the best way to ensure what you're writing makes sense is to always keep in mind what you're trying to achieve with your analysis. Something my Lit teacher used to say which has always stuck in my mind is:
"English is about the content of a joke, whereas Lit is about the way you say the joke".
I hope this helps, sometimes it's really useful to have a basic structure to fall back on. Let me know if you've got any questions