It has many way to do and many SEO expert already guided the way as above , anyway my key method as highly focus is.. 1. Find the good keywords (high demand products and less competition) 2. Built backlinks from quality website or blog
try promoting in classified websites, directories, exchange links, etc.. post in the website themirchi.com, it has featured listings as well as free listings which can drive customers to purchase your products.. http://www.themirchi.com For link exchange, post in http://www.themirchi.com/directory/
Own Website for Astore + SEO , I think this might work.. Also yes, Blog , Wordpress , Signature..etc...
For the work you put into it, it seems that the return you might get from promoting your astore is not worth the time and effort, unless you strike it rich with PPC.
Submit directory is just one way for that. make a blog or website and place aStore on your web/blog and submit them
You will be post to other forums and use signature links of forum. or submit dir or answer to answers.yahoo.com or drive traffic from blogs. or ppc. other...