Mistake # 1. Efficiency wasn't calculated
If you don't calculate the profitability of the planned project in advance, you run the risk of working at a loss to yourself. To help simple math: profit = demand * (revenue - costs). Is indicators satisfied? Then boldly go forward.
Mistake # 2. Not identified niche
It's a flight to nowhere. Why would a customer buy from a stranger what he can easily buy from a trusted supplier? Identify your "highlight", which will allocate you among competitors. If it isn't, you risk wasting money.
Mistake # 3. Didn't compose a content plan
It's the main way to attract visitors from search engines or social networks. Ignore it, means to lose more than half of potential customers.
Mistake # 4. Launched a contest without a plan
You attract a lot of customers to the site. What's next? There must be something that will make him come back: new shares, offer, updating of goods and information that can keep the buyer's interest.
Mistake # 5. Do everything by yourself
You are the programmer, and copywriter, and designer, and the manager in one person. But in this way you lose sight of more important tasks: finding new suppliers, developing new ideas for business development. As a result, you simply will stand still. No growth.
Mistake # 6. Didn't draw a portrait of the client
And whom do you sell all this? Even if you're trying to reach the entire target audience, you should segment it and find the buyer who brings you the maximum share of the profit. Otherwise, you risk directing an advertising campaign to the wrong segment of the audience and losing a significant part of your income.
Conclusion: explore the market and its customers, find a niche, make a clear marketing plan and you can run your online store. The probability that it will be successful, will grows by 70%.