Slip a piece of paper in her morning paper telling her to look outside her window. You should be ready in a tux and showing her the ring.
Pick her up for a date and then blindfold here. Tell her you’re taking her to secret destination. Once you’re there, lead her to the place you will propose, and then give here several objects to touch and identify, for example: a paper clip, a CD, a key chain, an orange, and then the ring. Take the blindfold off and then propose. For added fun, drive around for a while with her blindfolded, but return to her home for the guessing game and proposal.