As we agree to get together, I find myself trying to figure
out ways to interact with this person.
I appreciate this person (friendly over the years), yet just
a bit too often - she is sharp (unnecessarily) and sort of
negative about various things that I say.
(a brief example - I mentioned that I might like to work
in a particular field - and she snaps at me about that;
another example - when I had one summer job and told
her, she snapped at me and said "you don't want to do that"
(actually I was kind of enjoying the job).

How do I stop this snappishness?
It's like I want to say "please don't ruin my dinner with your
nasty bad mood - that's not what my presence is for"

Maybe it is for me to understand that there are probably other
reasons for her snappishness. But, I still don't like it - and I
don't snap at her (yet I have just as many life concerns as she
does).
So, the first question: how do I stop her snappishness?
Next question: what topics can I bring up to ask her about so that she stops targetting me?
How about 20 topics (considering that we have different educational backgrounds now). (actually I tried that one time - I wrote out a list of topics).