You must see SEO as part of marketing.
There are few SEO books on Amazon for entry level but dozen books in Taiwan and China. SEO is a very important issue for on line seller.
Even eBay use it for buyer and seller search items. I am not expert but I read some books and do by myself for our local web site.
Most SEO books are technical. Very few books for business management or entry level.
Google search engine algorithms is not just spider but also robot.
You may check "Google dance" meaning.
If You see top 3 ranking web site, the key words, you may surprise that they all optimize their web site.
So, you have to register your web site on google and Yahoo.
http://www.google.com/addurl/
second
I sell soap mold, so I put key word on my etsy shop.
http://kudosrichard.etsy.com, How I put my key word on?
For example, the web site, ranking Number one soap mold supplier,
http://soapmold.net/
Please see your browser top, you won't see shop name!!
You will see " Soap making | soap mols | soap making equipment | soap cutters". KEY WORD!!!
That means search engine read those words first.
You see the number two ranking soap mold seller, milkyway
You won't see key word on the top but what is inside?
, they put all key word in each category.
What is milkyway use key word? " mold" " soap mold"
So, you can use "milk soap" "body lotion" " promotion soap" for promoting your web site.
Third
Your web site must have site map. Most free shopping cart system have it. In case of you pay some money for hosting company. You shall ask them. Search engine will read it.
This is the reason, don't use blog for selling. It will not so easy promote your web site.
It doesn't mater how good your web site design. If no one find you, you will live in valley.
There are some free SEO software, please use it to promtoe your items before you buy SEO service.