Where are those that are looking for watches hanging out, asking questions, and looking to buy? This is the question you have to ask yourself and it is the staple question for what marketing is. Go to your most targeted visitors. Just some ideas, if you are selling high quality name-brand watches, then your best bet would probably be to advertise on fashion blogs that have real visitors interested in fashion. If you sale a niche of watches, perhaps sports watches or dive watches, then you might look into advertising on sports websites or scuba diving forums or blogs. The key is to go to where your target traffic is congregating on a daily basis and promote your products there. You know people are searching too, but watches is a crowded market. You should make sure you target the right keywords if you do search engine marketing.
Try promote your products on forums related to your niche (fashion, accessories, general, wholesale, etc), use the signature box to promote your website.
You can use craigslist, PPC advertising, affiliate program or buy signature or banner space on those shopping or watch forum. Besides, you can consider to join those B2B platform too
Perhaps you could get exposure through Ebay and other avenues. If you have access to some handmade stuff, you could get exposure on Etsy. Craig's is a good idea... Ebay classifieds. Perhaps there are tradeshows in your area? You could promote your store there, too.
I would like to second the idea of craigslist. Again, targeted visitors, but they are actually in the mood to buy, which is probably going to increase your conversion rates.
Facebook and twitter are good ways to promote your store, you can have a try. Uoften need to optimize it and promote your products, you can do Google ADs. In total, get more traffic so that you will get orders.
I been find out some people use social media but seem like not really work because they worry of fake brand and maybe costly. I believe u can advertise it in classified , directories and google adwords.
social media marketing and search engine marketing the best way, by the way are you for any specific geo location?