These prompts are great for art journals and sketch books!
1) Fill a page with icons. Think logos, symbols, flourishes, doodles, and other small and simple designs.
2) Completely cover a page (all white space) with leaves, feathers, flowers, and other things you find outside. Bonus points if you find butterfly wings.
3) Cut a pattern out of one page and use it as a stencil for the next page. Brush acrylic colour over top.
4) On a nature walk, pick as many varieties of mushroom as you can find. Try to determine what species they are, press and lable them in your journal.
5) Use a cup to fill a page with circles. Then, use different kinds of paint, pastels, markers, and fabrics to fill each circle in. Do the same for the gaps between the circles. Bonus points if none of the circles touch another of the same medium.
6) Paint stores give away mis-tinted house paint for free, or for very very cheap. Acquire latex house paint and apply large dollups of it to the page. Let them drip, focus on texture. Use a fan or blow drier to dry in place.
7) Sew along the edges of the page, loop the thread around instead of stitching so that it shows when you close the book. I used gold thread from the dollar store, it is thin enough not to get in the way of future entries.
8) Make a collage with old photographs and postcards found at a local second hand store.
9) Draw the room you are in. To avoid changes in perspective, stare at one object and draw what is in your peripheral vision.
10) Make pencil rubbings of the titles of all of your favorite books. Usually these are embossed under the jacket if the book is a hardcover.