As your business expands, you should Hire people to help with a few tasks like order processing, adding new products to the website regularly,
make sure that the inventory is complete and so on..
SEO and social media are very important.
I have had a show store which initially targetted low keywords and I was just acting like a affiliate to amazon and other stores..
But later on when I started to get huge traffic to my site ( I was targetting lot of low competition keywords with good search volume), I opened a shoe store myself and
earned very good money.
Use coupon Codes, vouchers, give freebies to regular customers, ask people to opt-in to your email list so that you can send them latest deals.
One strategy I use consistently is :
Create a nice image on facebook with my logo and then in the image I mention about a contest or something where
people need to download that image on their desktop and then tag my page and 5 of their friends to that page.
I will choose a random user and give his friends discount coupons and so on..
It helps me to get viral and get new fans to my fanpage...