Also forgot to mention you need to provide both idle and cruising Fuel Trims at some point.
If your car is running rich, the fuel trims will be negative or proceeded with a - sign, they will be displayed like -2.3%.
If your car it running lean, which happens most often your fuel trims will be usually not be proceeded with a value or + sign, they will be displayed like 3.4%.
In my world I try to keep my fuel trims under 3%, prefer under 2% but sometimes this is not very feasible.
Forget about anyone that tells you that fuel trims just below 6% are fine, they may not trigger a CEL but they are NOT fine. This is too close to the threshold for triggering the CEL.