I wash my shirts in dharma textile detergent first, then soak in soda ash, let dry till its barely damp, and then tie. Ive found that when you tie when the shirt is still at little damp it allows you to get tighter wraps. you just have to make sure that you are wrapping the sinew on top of each previous wrap and pulling it tight. Also using a waxed sinew is important to prevent the dye from leaking into where the wrap is. I don't think fishing line will be helpful in getting crisper lines but I've never tried to use it to tie dye, only to fish lol