Clean their rugs & Tail bags for the tail
If she/he gets to dirty i would use just plain water and try to hose them off. Or you could use a stain remover. Or you could spot shampoo him/her.
Hey! Try to keep the bed clean, rugs and hoods are great! I wash my mare with blue and white soap (we have bars of this soap, it leave the horses super clean and white) Hope it helps
Lots of brushing, for turnout maybe consider rugs and a hood. Try not to wash too often as it strips the oils meaning coat gets dirtier easy. When you do need to wash I would recommend using a blue washing up liquid.