The worst mistake which a beginner can make is absense of any business plan. Before investing in your own business, you need to realise how it will develop and how much money you need to make it bring profits.
The main mistake people make not only in business but in affiliate marketing is that they invest all their funds into a single source of income. If we take affiliate marketing - many teams find a working bundle and immediately stop looking for other ones. And when the bundle burns out, they fail to identify a new one and they also didn't allocate any money for tests. Meaning diversifying your sources of income is always a good idea.
I just see this thread, but even now, almost three years later, there are the same mistakes that people seem to constantly repeat. Besides things you highlighted, I would also say that lack of patience to see the first results of marketing activities is a huge issue, as this can make some people give up and they miss some great opportunities just because they didn't have enough energy and will to wait and see the progress.
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