It's mostly like eBay. Just buy what you expect. Its really helpful and safe!!! When you scroll all the way to the bottom on most websites, it sometimes will say "norton protection" and things like that.
Amazon is very safe. When you search for a product, always check to see WHO the seller is. For many items it will be Amazon.com but others may be a third party seller. In that case check their reviews and ratings, see if and how much they charge extra for shipping and their shipping times. Some sellers have a higher shipping fee than others. Stay away from sellers with poor ratings and you will be fine. I buy on Amazon all the time and normally get my stuff within 3-10 days!
I don't think it gets safer than that - its possible if you buy from a seller that the product doesn't work but this usually isn't the case. they've got top notch security because they can afford it. everyone trusts amazon.