Read the forums. Not only are there great people there, but there's a wealth of information there. Use the search bar at the top and you'll discover even more. All those guides for Etsy success? I'd be willing to bet there isn't a single thing in there that can't be found in the forums. You'll learn about tools to help your shop you never knew existed. Not sure about a picture or price? Visit the critique section. It's really not as scary as it sounds, promise!
Pictures, pictures, pictures. I can't stress this enough. You need great photos to be successful on any online venue. Buyers are not going to buy from you if they can't see the widget properly. If you have great photos you are saying you are a professional business and people should buy from you. You don't need a DSLR or an expensive light box. Search the forums for cheap light box instructions and get to know your camera's macro setting. Sunlight is free and the best light but OTT lights work well (or so I hear in the forums).
Some say renewing works and some say it doesn't. Pay attention to what the seller sells before you jump on the bandwagon. Those 20 cent renewals can add up quickly! Do a search for your items and see how far back they are. I noticed my altered clipboards were about 3 months in and I searched and found myself on pages 3 and 4. I'm not going to renew because a buyer will most likely go back that far. If you are on page 421 then renewing might be an option for you. If you do decide to renew to increase sales, use GA to keep track of views and treat it like a real experiment. Then decide if it helps your business.
Keep your fees low. Again, those 20 cents add up! I'm not saying to do fee avoidance because that's not cool. Etsy has earned your 20 cents and FVFs and it's still a great bargain to be able to sell your widgets. I'm just saying to spend those 20 cents wisely. If I have a buyer that wants a custom order and I know they want X, Y and Z I will make a new listing with everything in one spot. I save 20 cents for each extra widget they order. If I am offering 5 widgets in a single listing and someone convos me and wants 10, I edit the original and link them to that. When I relist it shows back up at the top. Now I just said renewing doesn't always work, but this free so what's to lose?
Lastly, what works for one shop may not work for others. I get sales from Twitter, others don't. Others get gobs of sales from Facebook. I don't (at least that I know of). Experiment, play, and have fun determining what works for you.