Due diligence before buying

I am not a good judge of what is real and what is fake, so for items that are really expensive, I would go to reputable sources.

Like gold bars, for example. I know people invest in them. I'd rather get certified gold coins from reputable companies rather than risk my money on coins or bars that may have the same weight but which I'm not sure of. I mean, I'm no expert in such things. How would I know if I'm getting the real thing?

I'd buy such things from a reputable company to protect my money. If I'm not sure about the company's reputation, I'd do some research until I'm sure that it didn't scam people before. I'm currently reviewing the US Gold Bureau and so far they seem to be legitimate and reputable enough.