Aside from SEO, what other methods that helps optimize a site?

CONTENT CONTENT and still CONTENT...it is very vital that a website has quality contents because content is KING on SEO.If users find your site useful they would be coming back again and again gaining your organic traffic.

i have Packing website, so help me how can i promote it? i am searching forums regarding it but didnt get best result. do you have any idea?

I have mentioned it before and I would say it again.Create a blog on your website stating the usefulness of your products or service.Update this regularly and your readers would be coming back for more.This is some sort of onpage optimization.