I think a marketing plan should include business cards, a tri-fold flyer with colored pictures (as a fancy resumé), a demo CD of excerpts if you cannot manage a CD of full-length songs, and a Web site.
Sending a CD is fine…. But make it teasers, break a piece off at the middle of an interesting art and leave it there. Send a rate sheet and set your rates to reflect the value of your art. If you are to sell your art, then sell it at a fair price.
Giveaways DO NOT WORK, snd Discounts is what you do with CHEAP product.
My daughter struggled with her portrait art for years until I told her, stop giving it away; raise your prices, stop lowering them; and go in with a fixed price that is not open to negotiation.