I ' m probably not the oone to be answering this because I have 2 baskets & a shelf of ufos.
My ufos are all from ideas I had that did not work out as I anticipated, or classes I took & did not finish there soo it went on the pile.
So rule #1,,, finish what you start. If you start my bad habit, they will never get finished.
Rule#2, allow yourself enough time to complete a quilt. Many of my ufos are because at the last minute I decided to make a gift too close to the due date, missed the cutoff,, & onn the pile it went.
Rule #3 , if you do start aa ufo pile, review it periodically. Sometimes there is one in there that can be repurposed.
Rule#4, keep fabrics together for a quilt. I have quilts I started, accidentally used some of the fabric in another quilt because I had put it back in my stash shelf. Now if I wanted to finish the quilt, I either have to change the look with substitutions or make something else.
These are the rules I would now follow if starting out, but as an old dog is, i' m too old to retrain. Old habits are hard to break.