Feedback is my most important because if there's no previous history of your transactions, then how do I know if your legit or not? There's a lot of scammers online and this is what the internet brought along with convenience. So before I buy anything from a seller on eBay, I look at the ratings and read feedback of the seller. Most importantly, you have to read negative feedback because that's what you want to look out for.
To start with, if advertise on eBay, I look for a similar alternative elsewhere. I have read so many horror or scam stories associated to eBay that It has to be something that I want so much and is not available elsewhere to get me convince to buy through this place.
There are a few things that I look for in a seller, especially if we are talking about Ebay. The first thing is their feedback rating, and then after that I will check to make sure that they have the right policies - like if anything is wrong with the item, they will pay for the return postage and packaging and such. Then I will read their most recent reviews, both negative and positive.
I mainly go for seller review because it shows how seller is trustable. You can search on google for seller review if ebay site has not sufficient..
I'm very careful when I shop on eBay, even more careful than on some of my online shopping sites. I look for the number of transactions, check the seller's overall reputation, go over the feedback he's received (both negative and positive), among others. Where the seller's based is a big thing for me, too. For instance, I refuse to buy from the Far East. In fact, I generally buy from UK sellers, and maybe the US sometimes. Those are the ones I really bother with.
Even if a seller on either Ebay or other shopping websites has a good seller feedback rating overall, I will still go to the feedback section to read what their negative feedback was, and if I discover that their negative feedback involve anything that seems too shady, then I just won't use the seller at all. There are certain things that I won't put myself at risk for with sellers, no matter how good their overall rating is.
I look to see where they're from. If its something I can't wait too long for I make sure they are in the US. If its something that I have time to wait on, I just make sure they aren't from China, usually. And as long as the seller review isn't too bad, I just look past it.
As a previous poster commented, I also look at everything. When it comes down to eBay, I look for ratings, reviews, previous transactions. I look for anything and everything that will tell me about the seller. I think it's very important to get all the information you can about the seller before purchasing an item.
I scrutinize everything even his/her profile picture. Before I purchase anything on eBay I make sure to Google the hell out of the seller before trying anything. Of course the stars and the comments help out a lot but researching about the seller for any past faults is a great way to get a trusted deal. I also try to avoid sellers that are fairly new and those that don't describe and post enough information about the product they're selling.