One of the first and most important steps of getting into the serious trading scene in ESO is to pick a trading guild. There are a lot of points that should be taken into consideration when looking for a trading guild that will be most ideal for you, such as the location of this guild and whether or not the items that you will most often be selling will sell well in said location. The culture and history of the guild (or guilds) that you pick also play a role in how successful you will be at earning gold, seeing as more competitive guilds will force you to adhere to more competitive selling strategies (like selling in bulk and undercutting), and guilds that are newer or have problematic histories may not always be able to secure a trader in the location that you'd like, or even any guild trader at all!
To learn more about how to find the best trading guild for your playstyle and interests in ESO, check out my video that discusses all of the factors that you should be considering before applying or sticking with a trading guild, as well as some of the trading strategies and practices that will help you succeed in a variety of locations.
I have written an accompanying post on my website that also includes a tier list for all of the trading locations in PC NA, as well as some more trading pointers!
https://tamrieltradesecrets.com/2020/12/26/the-best-trading-guild-locations-in-eso/