This has changed over time. I always started with an idea that at least I think is original. Come up with a couple of ideas for stories around the idea and then decide which one to pursue. I use to just start writing from there and see where the story took me. I have changed and now I plot out my novels with a 5-10K chapter by chapter synopsis before I start actual writing. I generally try to write through a first draft, but invariably, I will go back and start a second read-through and edit before I finish the first daft. My first draft is to get the story down, but it is not something I would ever want someone to actually see. I will go back over the manuscript several times to get the dialogue right and flesh out parts that seem too bare. Cut back parts that are too verbose. Make sure what is left flows well.

I actually only write part-time while teaching full time at a local university. When I have rare free time, I like to spend it, fishing, hiking or camping.

My first books were all by Dr. Seuss, and I was just enamored by the colors and imaginative worlds portrayed. I remember soon after finding a book by Eleanor Cameron called The Wonderful Flight to the Mushroom Planet in the library of the elementary school I where I went and was carried away by it. Immediately afterward, I started seeking out other sci-fy books in my library and came across one by Robert Heinlein called The Moon is a Harsh Mistress. Those books were a lifetime ago, but I still remember some of the scenes playing out in my head as I read them.

Ooh! This one's tough to limit to just 5 books, but here goes. Keep in mind my top 5 may be different a year from now, and these are not in ranked order. Spoiler Alert ahead for some of my reasons. All for the imaginative worlds portrayed, but also for the stories told.
Hyperion by Dan Simmons (The story of how the father had to deal with his daughter aging backward was heart-wrenching)
Old Man's War by John Scalzi (I am not sure why I love this one so much. Perhaps it's because it's written from an old man's POV)
The Forever War by Joe Haldeman (What can I say? If you haven't read this one, you should. It is a classic beyond just SF)
Harry Potter and the Deathly Hallows by J.K. Rowling (The way Rowling flipped Snape's role in the book just blew me away.)
Foundation by Isaac Asimov (This one probably more for nostalgic reasons that anything else. It was an early read that I could never get out of my head.)

I read on my Kindle Fire.

This may be a little strange because most authors (I think) don't enjoy editing. They like to just sit down and type, but I enjoy the process of going back and editing by drafts. Getting the first draft done is sometimes a struggle with finding the right scenes to drive the story. The editing is where I can take something I wrote that is dull, pitted and otherwise flawed and make it start to shine and really come to life.

I am in the process of the final polishing of the third book in the Dinosaur Country Series. It is tentatively called Definition of a Monster. You can let me know what you think of the title. I am also just beginning the first book in a new series. This is about an archeologist and his team set in the far future as they try to find evidence of past alien civilizations. However, once they find something, they get themselves into a bit of a jam with the local wildlife which turn out to be monsters, not to mention they are sort of lost in terms of how to get back to charted space. I know, how can you really be lost if you can see other stars, pulsars etc., but traveling through alternate space is not so straight forward.

Long list: Isaac Asimov, JK Rowlings, JRR Tolkien, John Scalzi, Joe Haldeman, Ursula Le Guin, Dan Simmons, Martha Wells, Frank Herbert, David Brin

I usually look through the top sf books listed on various sub-genres on Amazon. I have a lot of Facebook groups I follow and also get recommendations there and sometimes pick up on books by indie authors from some of those sites.

I wrote a story I called Under the Dome while I was in high school. It was about a town of people who suddenly found themselves trapped under a force field type of dome. Keep in mind this was many decades ago that I wrote this. On the other hand, it was not well written. I no longer have the manuscript and really have no desire to see it again.