Place paper images of leaves onto a cutting mat.
Cut out each leaf using the X-acto knife and set aside.
Mix water and trisodium phosphate cleanser, following the manufacturer's directions.
Scrub the wall to be decoupaged with a sponge, water and cleanser and allow it to dry completely.
Apply a thin layer of the gloss medium to the back of each leave to glue them on the wall.
Rearrange the leaves on the wall until you find the positions you like. Press the leaves to the wall firmly, creating a firm seal between each leaf and the wall.
Brush a layer of gloss medium over the leaves and surrounding wall using the foam brush and allow it to dry.
Repeat Steps 9 and 10 until you have created a smooth, glassy layer over the leaves and the wall.