Search:

Google or any search engine like quality backlinks from good DA sites.

Firstly ON page optimization is must for E-Commerce sites. Write unique and detailed description of your product. navigation should be easy.

Then start OFF page promotion:

1. Email marketing:...

It depends on website size. WordPress is not good for big sized website. Magneto and Joomla are good. But Magneto is developer friendly, not the user friendly. You need a professional efficient...