Thumb rule: The longer the information in the listing, the better. If I see that a listing has very minimal information, is it a huge turn-off for me. Why? It shows that the seller doesn't take their business all that seriously and chances are that you will get some lousy customer service in case you have a question about the product. For example, if you want to buy earrings and the only description it gives is 'Gold. Brand new condition.', it should be a major red flag. In fact, it might not even be hand made. Opt for something more detailed, like:
'Gold coloured earrings in a heartshape form. Made from *insert material*. Completely nickel free, so suitable for those with a nickel allergy. Also available in clip ons, just message me and I can change it for you. For any questions, feel free to contact me. *Insert more information about the brand, policies, blah blah blah*.
When it's for cosmetics: it's best when they list the ingredients. If they don't and it's nowhere to be found on the site, it is not looking out so well (although you never know for sure until you ask them about it).
Semi-relevant, but not unimportant: Take a look at the pictures. This doesn't always mean that if the quality of the image isn't fantastic, the product must not be good, but it is a guideline. Good, consistent pictures are always a good thing and shows professionalism. Stolen pictures without crediting the maker is a very big no-no. Not calling names, but I once saw a shop using pictures from a very well known makeup artist and said: 'Don't know who the person in the picture is but the colour is similar to what she's wearing'. Not sure if I wanted to laugh or cry when I read that.
Google the brand before buying. Online shoppers are in general very familiar with the concept of googling reviews before buying the product. And even though there might not be a lot of reviews about indie products online, googling the brand itself is always a good idea. In case a customer has had a bad experience with a shop/seller and the problems was not solved, they are very likely to turn to the internet itself, like social media or sites like Reddit. Personally, this has saved me multiple times before purchasing from people that don't handle their business well, are unprofessional or not a very nice person. So when in doubt: google.
Take a look at the rating: it is there for a reason. When there aren't any reviews online, the shop rating is another reliable source, or in fact, the first thing you may look at. Also for this topic the size does matter: the more sales, the more reliable (unless the shop was opened very recently). Take a look at the reviews as well. Needless to say, if they are positive it should be good. But the most interesting reviews are the bad ones, because sellers have the option to respond to that review and have a last chance to solve the problem that caused the low rating. If they show to make an effort to make the customer happy it is not always a guarantee for good service, but it's a safety net.
Just a last reminder to stay out of the hands of these fellows!
Are you an Etsy fan? Do you have additional tips?