Profit is the most important thing for bootstrapped businesses. Meaning that your Shopify store is self-funded. This is the case for most Shopify stores. therefore it's important that you find ways to increase your profits.
The hardest thing with any online store is generating sales profitability. If you could just continuously do that your store would be doing great. Where as ads can be unprofitable or break even.
Website organization is key to helping your customers figure out what they want to buy. Except Shopify's menu structure lacks some key features mega menus have. Making it hard for larger Shopify stores
Making sure you can address customer issues as soon as possible is key to having successful e-commerce. Many customers have questions before they purchase something. This is especially true when they are purchasing
Amazon is a great second sales channel to sell your Shopify items. It requires no additional paid advertising to start. It's the world's biggest online marketplace so there is no downside to listing