This is a scan of the notebook page where I was writing my personal questions and (tentative) answers. I would love a notebook that had lines for writing on the left side and a blank facing page for sketches but have never found one like that.
The main questions to answer were, what material to use for the base, what construction to use in making that material into curtains, what design aesthetic to use, what material to use to work the designs, what color should that material be, and what stitches should be used in working the designs.
As is often the case several of the answers were essentially a "given". For every project there is likely to be at least a couple of already determined answers and it's good to identify and get those out of the way quickly. In this case the curtains need to fit with the color and general style of items that are already in the room.
This means that the colors are rich reds and greens with warm neutrals, and the style vaguely Asian as I like Art Nouveau and styles that have both lines and curves.
Because I want to use the curtains before we move, which seems to be about every four years and we've been here three, I know that I don't want to *make* the base material of the curtains as I did with the wallhanging. Because I don't want to spend a lot of money I don't want silk, satin or any "high end" fabric. And, since I plan on doing needlework on the curtains but still need *some* light to come through, I don't want too heavy or solid of a fabric. This leads me to reclaimed coffee sacking from a locally owned coffee shop that roasts their own beans. Along with being a warm brown that fits the colors of the room, so I don't have to work over every bit, it is inexpensive, meets the other requirements, and fits my personal aesthetic of running as close to zero-waste as possible.
So now I have my base material, working colors, and general style questions answered. The answers don't always come in the same order though. A lot depends on what the inspiration was as that will decide the first answers for your project. Working from the base to the extended details, filling in your "given" answers at the beginning, is generally a safe way to go since the base can be prepped while some of the other questions are still being answered.
The practical preparation decisions will be the focus of the next post since this one is getting sort of long.