I've used several marking tools over the years. My first sewing teachers taught us to use the transfer paper for marking darts. My mom used a special white pencil for marking. My teacher in college showed us that we could mark the dots with thread that could be removed later. This worked especially well if the garment was sheer or if I didn't want the markings to show from the other side. Six months ago, I tried the Mark-B-Gone pen, but it dried up so quickly, I regret the $4 I spent on it.
Lately, I open up my desk drawer and take out whatever marker strikes my fancy. Today it was a Sharpie.
My fabric is thick and dark enough that it won't show through. I don't have to worry about the markings fading or rubbing off (as with chalk). Most of the sewing gurus would not agree, but this is my easy free solution...and it works!