I'm 4 classes away from my BA degree in advertising. I already have a BA in finance, though I don't like this area. My question is what is the best way to find a job in advertising/sales?

What aspect of the advertising team will be your specialty? If you have no direct experience, find a smaller company to target. As a new person to the field, you are going to have be able to sell to them to meet their needs specifically. So as you look through job descriptions, look for those specific markers that you will need to elaborate and emphasize in your cover letter. As always, know about the company you are applying for. For example, ABC Advertising has run a classified asking for a specialist or whatever along with skills and experience preferred. With the exception of those that state they want several years experience (versus at least one year), send your resume anyway. If you get an interview, you will need to know the method of advertising they do, the distribution and also about their direct competition. Armed with these things when you go into an interview new to the industry shows your level of interest (instead of the first job you could find) and shows your comprehension of their business. Good luck.