I have a InDesign file that is 20,428 KB. I would like to convert it to a PDF no larger than 10 MB but stay as close to 10 MB as possible to preserve as much detail as possible. How can that be done?
The size of the ID file is immaterial as it does not take into account the size of the linked images/graphics.
I would start exporting at the top end (i.e. Color Images: 300 dpi images, Image Quality: Maximum), see where that lands you, and work backwards from there.
Start with changing the image compression; e.g try Image Quality: Medium.
I wouldn't go much less than that as the compression artifacts will ramp up considerably.
If that doesn't do it, try reduce images to 200* or even 150 at Medium Quality. (I personally like 200 as it still gives a goood print reproduction ratio)
Where file size is an issue, I also try beginning with a high res PDF then try the Save As... reduced file size option. It might not always do much, but it 'cleans' up the document by removing all the unecessary background information and structures.