I use tailor chalks just like Debra's pic, pounce pads, markers and pencils. Blind as a bat. The pencils are the least visible for me.
Tailor chalks can be found all over but Jinny Beyer has them, too. They're good for smaller projects. My Gran used to spray the markings with something to make them last longer. If I did that, they'd probably last forever.
Never used soap but had a neighbor swear by it. Might be worth a try except we don't use bar soap here. :0D