As far as getting into the advertising-music industry, you need to create a "reel", which is a demo used to promote your services. This can be done very cheaply nowadays with inexpensive home-recording equipment and a CD burner, although if you are going for "big brands", you would most likely need to do a demo in a recording studio to get the best quality possible.

Then, you must take the time to create a few professional documents describing what you can do for THEM (the businesses that you will be approaching).

After you have everything ready, it's time to make appointments to meet with business owners. The biggest thing to remember is that you are there to help THEM make more money...since that is what advertising is all about.

Another thing to remember is to always be flexible. You must not allow yourself to get to "attached" to you work. Often, once the demo is heard, there are changes that need to be made before you have a finished product.