Assuming you have a quality product that people want to buy, to find your market and strategies that will work for your brand I'd run a bunch of small marketing experiments in different areas (social, ppc, influencer, affiliate, etc)... see what works, then go hard on that channel.
- FB cold ads usually take time to figure out and get dialed in. I like FB for remarketing but not much for cold marketing unless you have a really unique product or laser targeted audience.
- Google Ads are great for testing and getting sales, I'd start there. If you're not converting at least 1% of traffic with Google ads, you can probably assume either your product or funnel isn't working well.
- Some brands do well with Instagram, some with FB, some with Pinterest, some with Twitter... you might try figuring out 1 social network then try publishing content / building audience on 1 channel. This will depend on the brand. I like Instagram for product brands.
- Email marketing is great, and there are some nice apps to automate this. One thing most people say is "I wish I would have started collecting emails earlier". I'd set up an email capture and start an email strategy early on.
- To answer the title of your question: try to be unique and inject personality into your brand and messaging. There are so many places to buy stuff online, you need to either have a cool brand, amazing products, a purpose, or some other reason to buy from you instead of the others. Connect with your audience on an emotional level.
- You mentioned you built a "general store". I think you're going to have a really hard time making that type of store successful. There's already a giant general store called Amazon :) ... most of the successful stores I've worked with have a clear niche, clear target audience, and invest in good branding/messaging to provide a cool experience.
ABT - Always Be Testing 🤓
Theme design is crucial because it's a main factor in conversions (the other main factor being the quality of your audience).
For your other questions, I'd consult a FB ads expert on those. I've done some successful FB ads myself and worked with people doing well, but personally am not a FB marketer so can't give you the best advice on specifics.