Wow! There's some great advise here. Here's my 2 cents worth, so it may not be worth much.
At an art supply store, I bought a sheet of vinyl. I lay it on top of the top and draw with dry erase pens. Don't like it-wipe it off and try again.
There are lots of books with patterns for quilting. They can be photocopied to any size that fits your quilt. Use a light box/table and make the top before it's sandwiched.
There are companies with patterns. My favorite is Digi-tech, on the web. Their service is great. You can order the pattern in the size you want.
There are many companies with stencils for quilting. Golden threads has a pounce powder they claim doesn't rub off, takes a warm iron. Has anyone used it? Whenever I use chalk powder or markers the marks rub off before I get to quilt them.