I have found the vendors that we use right here on ECF, usually in the eliquid forum. I also like to check the reviews on the vendor websites. There are some vendors who publish all reviews, both good and bad. I also like vendors that provide a brief description of the flavor notes the eliquid contains. It is all well and good to have a catchy name for an eliquid, but if I can't find at least a brief description of what the flavor is supposed to taste like, I don't buy it.
In the end, though, it all depends on what tastes good to you, with your equipment, and meets your budget. The recommendation to order small bottles at first is a good one. If you like the eliquid, you can always go bigger on your next order.