Use diluted ammonia, for more stubborn stains, use undiluted.
I have found Tile and floor care’s “Mould Buster” to be very effective.
Or use Oxalic acid, mixed with water. (Take great care it is highly toxic)
PAINT ON MATERIAL AND CARPET
Use ”Polycel brush cleaner”
Ball point pen ink:
Sponge generously with methylated spirits or try working a little white toothpaste onto the fabric and wash with warm soapy water. ( Loosen old stains with glycerine and detergent.)
Crayon wax:Sponge with Meths and launder, or use benzine, working from the outside of the stain, inwards. Launder before the benzine dries. For non-washables sponge with a damp cloth before benzine dries