According to you which is the best for any fresher person?
Marketing for sure. As mentioned above there aren't much sales without marketing. Even with sales, having a strong marketing campaign is still necessary. Knowing the difference between sales and marketing is crucial, and knowing how to use startup marketing is key. Here are some basic marketing venues.
Direct Mail - Easy to design and cheap to produce, this can help you reach target demographics.
Social Media - Basically free in most cases, this can help your site generate organic links.
Blogging - Join your industry and offer useful information to your customers. Also a great way to generate organic links to your site.
Guest Articles - Also a great way to market your site and show your expertise, guest articles can be written for various submission sites or other blogs.
Video - Simple videos that highlight what your business can do are great for building exposure and offer cheap and effective advertising. Just be sure that your video is edited and produced with quality.