Focus, I can't say it enough times. But where do you focus on? And when do you focus on something and when not?
Focus starts with having a good night rest and drinking enough water. Next you will need to know where to focus on. Luckily, ESO has a very clean user interface (UI). The UI however lacks some basic elements for you to succeed in becoming a good ESO player. You for example can not see how much damage you deal and how much healing you receive. But before we go into that subject, lets take a look at what is available to you when you first launch the game.
On you screen you will see some very basic elements: Magicka, Health and Stamina. These are the basic resources you need. And you really need them. Most importantly you need to keep your eyes on it all the time. You don't want to be spamming your healing or damage abilities and not notice you ran out of resources about 20 smashes earlier. Therefore damage dealing and tanking characters should always keep an eye on their magicka or stamina bars (depending on your resource focus) and healers should always keep an eye on their magicka (since most healers are magicka based) and their own and their group members' health bars.
Focus your resources
During your adventure in Tamriel you will level up until you reach the max level possible. When you level up, you receive an attribute point. Which can be spend on resources. Determining where you will put those attribute points before you place any of them, will be greatly beneficial to your progress and performance later in the game. For example when I started on my character Argorn Nightsky, I predetermined which role he was going to fullfill. He had to become a powerful damage dealer based on stamina. Therefore I chose to make him a Nightblade and let him be a Woodelf (Bosmer). Because I already set an objective, it was easier to decide where to put my attribute points. Namely mostly focused on stamina and a tiny bit into health.
Keep an eye on it
So depending on your role in the world of Tamriel and your resource focus, there are different UI elements to keep an eye on. But the basic UI lacks some key elements which can greatly improve your play. The answer to this issue are addons. Downloading and installing addons which enhance the UI can be of great help and are not that hard to manage. For example the third-party software Minion offers a very easy method of installing these addons. One key addon, a must for all players, is Foundry Tactical Combat (FTC). This addon allows you to see combat relevant information on your screen. It shows damage dealth by your character, damage received, healing done by your character and healing received in scrolling text. Which allows you to finally understand how much damage you are dealing or receiving and how much healing you are giving and receiving.
Knowing how much resources you spend and how much it delivers, makes it easier to manage your resources and start using the more efficient. Keeping focus on the relevent information in the UI will greatly improve your performance. Because that is where the magic happens, the rest are just some adorable visual effects. And predetemining on what resource you will focus and which role you want to fullfill in the world, will save you some in-game cash and make progress in large steps more obvious, which is more rewarding than taking tiny steps.