@muiphan Remember that every other person wants to rank on google top page as well, so you have to do more / be better than them to rank.
Back links are the single most important factor, in my opinion (I worked as an SEO consultant for a few years and ran various experiments).
That assumes you have all the basics, the things you can control on your site. My favorite resource for people gettings started with SEO is https://moz.com/beginners-guide-to-seo.
To get more backlinks, look up “backlink strategies” in Google to get ideas (that guide above will give you ideas as well), or hire a professional SEO consultant to lead a program for you. When you’re prospecting people to hire, ask for case studies and customer testimonials.
One of my favorite backlink techniques for ecommerce sites is to create an affiliate program. Then create an army of affiliates, all linking back to your site (because they’re incentivized it will be much easier to get links), from blogs, youtube channels, etc. Check tip #2 in my 7 Shopify Automation Tips Guide: https://orderautomator.com/shopify-automation-tips#tip2.
SEO is just 1 part of your business, if you have the resources, I would try to hire for it, even just a 3 month project, with a good SEO consultant that will give you permanent results. If you’re strapped for cash, you could try hiring an intern, someone that is aspiring to be a professional but needs experience. You might not get the best results but with basic knowledge they / you can provide a foundation level strategy that will help.
Blog posts help really well, but you have to be consistent (at least 2 articles a month I would do), and it will take time (6 - 9 months on average), and your content has to actually be good and useful (people land on the page, read the article, click your links, etc).
Good luck