One mistake people make when they look for investment advice online is to fail to set out specific criteria in advance of their search. There are an enormous number of investment websites covering any topic you care to research. What, specifically, are you looking for? How much detail do you want? How much about the topic do you already know? Having answers to questions like these can make your search more productive.
Another mistake is to take a website at face value. Does the website promote a particular viewpoint to sell a product or newsletter? In investing there is no Holy Grail, no omniscient pundit. Seek alternative points of view. Be skeptical at all times.