How can I decorate/ organize a playroom for small kids?

Some paint and some wall stickers that can be easily removed when children grow up. Also some colorful accessories and if you want to change the room without too much money rearrange the furniture to make room feel good.

That would most likely include at least one toy box. I saw one playroom that was painted white with red and blue stencils of the kids favorate sports activities (baseball, auto racing, horses, etc.)

You should have some kids books, teen magazines, some books that you like, and maybe like, pictures in the bookshelves. Get bins to put in the bookshelves and fill them with toys, drawing supplies, arts and crafts, etc. Label the boxes! Clean up the play table and put it in a corner, but still make it accessible from every side. Put the futon against the longest wall and suggest putting a TV in there.

Try buying some sheet-chalk board stuff, or paint that turns into a chalk board. It will save a little room and give him something else to play with (like colouring on the wall with chalk is okay!). It's durable, washable and easy to apply, and can pretty much be found at any where almost.

I'd say paint one wall each color, get the big foamy floor mats that can interlock like puzzle pieces, or can be rearranged like hop-scotch tiles, and build/get a few storage box benches - useful and dubs as storage.

Make "L" shaped corner that could made into shelving with tubs that you slot into it for storage, and tall enough where they can make a fort, or you could do hand puppet shows and if you build it correctly, you could have one of the boards fold down and become a low table that's easily "hide-able".

https://www.extraspace.com/blog/home-organization/room-organization/playroom-design-ideas-your-kids-will-love/

https://www.hgtv.com/design/rooms/kid-rooms/kids-playroom-design-ideas-pictures

Here are some sites for you to grab some ideas from:

https://www.extraspace.com/blog/home-organization/room-organization/playroom-design-ideas-your-kids-will-love/

https://www.elledecor.com/design-decorate/room-ideas/g25938283/playroom-design-ideas/

https://www.thespruce.com/how-to-decorate-a-playroom-4079217

https://www.pinterest.com/daynars/decorating-ideas-playroom/

Try shopping second hand and thrift shops for bookcases and or toy boxes that you can easily upcycle with a few coats of paint to unify things. They should have a table and chairs for drawing, coloring, arts and crafts and even snacks or lunch and the occasional tea party. Make each one a bulletin board to display their artwork and treasures. Wal-Mart has nice ones for $8 to $10 And you can use craft paint and stencils to personalize with their names.

Get some furniture at a thrift store such as bookcases, old coffee table (for coloring) small table and chairs. They can be painted creatively or left plain.