1. Buy some contact paper at your local crafts store, dollar store or Target (they have great patterns!). Then, come up with some designs that you'd like to try. Trace or print them onto paper at the size you want to make sure they are exactly what you want on your walls.
2. Trace your wall decal design onto the contact paper and then cut it out with your knife or scissors. Be careful not to cut yourself or anything under the paper.
3. Tape the cut-out design onto your wall to make sure you've got the wall decal exactly where you want it. Then, once you've made any adjustments you might need, peel the back of the paper off and press onto the wall. Remove the tape, and you've got a great homemade wall decal!