..what one thing would you like to do better?
I struggle getting emotion on the page, so that's the biggest thing I'd like to do better. Probably too much time writing newspaper stories, business and financial to boot. I've read books on emotion in writing, characters, etc., including one on method acting which helped the most. Now I write early drafts with every POV in the first person, then change to third later. The extra work is a pain, and nothing I'd recommend to anybody but those of us who are ...uh, emotionally challenged.
Emotionally challenged. Includes most people with XY chromosomes.
Senses. I'm okay describing what people see, but I'm rarely able to describe what they smell, taste, touch, or hear in a convincing manner. it always reads like a decal applied after the real writing was done.
Like Dana, I'm mostly visual. Yes, I'd like to remember getting other perceptions in. This tends to be description, for me a matter of style. As a rule, I press forward with the action. I need to slow down sometimes. And putting the niceties in later rarely works for me.
For me the visual is easy, its doing good narrative and knowing when to use it.
Studied to have become a plumber or auto mechanic instead.
Money instead of fun?
I mean that plumbers and mechanics make more money than writers. I took this to be your meaning.
... find that compelling story, the 'McGuffin' that people find fascinating. What will make the book stand out from the others on the (virtual) shelf?
To the folks on here who've commented about getting emotion on the page, can I recommend Donald Maass's The Fire in Fiction? I finished it last week and it was very helpful in respect of this issue. He's very good at finding those problems that writers have, discussing them with examples, and then providing exercises to help you flesh out/soup up your current work.
Two major things: Believable voices and logistical plot devises. I suppose the former is a matter of preference and opinion but I do struggle with the latter. A lot of "get from point A to point B" moments in my stories end up being logistically awkward, or worse. So that's definitely an area I need improvement on.
With prose work: involve the senses to promote setting without "seeming" as if I'm doing so (Walter Mosley has a particular talent of doing this very thing seamlessly in my opinion). With my comic book scripting: learning how to get more with fewer pages.