Tissue paper flowers are fun to make. Get plain ornaments and cover in colored paper. Cut out arc in cardboard and use crumpled tissue to make the colors of a rainbow. Get pictures from a coloring book use tissue paper to color. Cut out various forms (leaf, lantern, etc) and turn it into stained glass.
Wreath - Cut cardboard, donut shaped. Cut out tissue papers in 1" squares. Wrap squares on eraser end of a pencil. Dip end in glue. Stick to cardboard. Repeat!
Author Eric Carle uses tissue paper to make illustrations for his books (The Very Hungry Caterpillar). His website shows him doing this, so you can learn how to do it.
If you have bleeding tissue paper, you can make paintings with it. Just take some elmers glue, water it down and tear up pieces of tissue paper. You can paint the pieces with the glue and make beautiful paintings.