Well, I think I'll just answer my own question. Elsewhere in these environs someone started a topic "I can't even imagine how to get started." (But maybe it was "...how to begin.") At any rate, Old Hack replied as follows:

"Here's how I did it, years ago. I've shared this with several friends over the years and so long as they put the work in, it always worked for them.

I listed what I did for fun, the things I knew about, the places I felt secure. So several years ago I was keeping a lot of poultry, living in a big house which was a renovation project, and looking after my young children. I knew a lot about those three things. Then I looked for specialist magazines which dealt with similar subjects, and I bought a few copies of each. I worked out a list of ideas for each subject, and pitched them to the editors.

I got work. It didn't pay much. Perhaps 50 per thousand. But within a year I was writing for the national press, and earning 350 to 500 per thousand. Much better work.

I did work hard at it, I invested time in my research, and I always delivered good work, on time."

I asked essentially the same question. /blush

Now, I am off to find out a way to get directed practice in writing queries. Learning goes slowly for me without feedback, and at my age, there is no time for trial-and-error based on guesswork.