The first step seems a bit obvious: do your research. A quick Google search can tell you at a glance what that brand is all about. Knowledge is power and can make the difference between getting a great deal on a quality item, or a good deal on something not worth your time.
What I will generally do is try to find the exact item I’m looking at on a different website. What does the product description say? What do the customer reviews say? Are there any other pictures? These are all questions I look to answer. If I can’t, I’ll research the brand. Here’s where I made an error recently: I assumed a brand was OK because there wasn’t any bad press on it; there was simply no press on it at all. No news is not good news in this case, a brand should always have something said about it.
Now don’t get me wrong, the item I ordered was great and I was happy with it, I just felt deceived that the high-end brand that I thought I was getting was in fact a fictional brand created by the website selling it. Always do your research if you’re in doubt!