Hello there! As far as guaranteeing you to have a winning store right off that bat that will solely depend on the product/niche you’re in. However I can guarantee that I can help build you a beautiful website that sells with the top tier customer service experience.
I’ve been currently working on one of my shopify stores in one of the most competitive niches in e-commerce (watches and accessories) as well using a premium theme (Turbo theme from outofthesandbox). I also have optimized my website speed to be faster than all of the biggest retail brands in the industry like MVMT, Timex, Fossil, etc. I currently manage everything and can do all of the skills listed below.
So to sum it all up, I can help you out with deciding on a niche or particular products if you haven’t already, building a beautiful website with SEO, logo design, HTML, installing the essential apps, picking the right theme, facebook ads, setting up your social media pages (with some free post automation tools), setting up a professional email, writing product descriptions that sell and with SEO, setting up pages/navigation, writing up legal policies/terms of service/shipping/returns/FAQs, setting up a live chat service, some free general consulting, and anything else that I may miss on this list. Unfortunately I cannot share my website, but I can send screenshots and my certifications on some of the skills I listed on building a shopify store, Facebook ads, dropshipping, SEO, and more.