Many new brands and products have come to the market since we had a playroom in the house, but still, the MUST HAVES are the same.
Then, group the items by different categories. That way, it's easier to evaluate the space and storage, shelves and baskets, needed.
To exploit the shelves at a maximum, select baskets of different colours, which also make it easier to classify and (hopefully) help put back the toys in the right spot.
If you prefer to limit the usage of colour, attach a photograph of the content on the basket and/ or write it on it!
I can imagine that sometimes kids don't want their drawings being wiped off. Give them the possibility to draw or paint on paper or rolls of paper in order to keep some of their creations.