if it’s sweet and you haven’t added acid, add a splash of vinegar.
if it’s too hot, add fat
if you burn it, throw it out.
IF you taste it early, it should taste weak. If it’s fantastic when when it starts to simmer, it’ll be too harsh once it’s reduced.
Taste it and it tastes empty or boring? Smell it. Smell all your herbs/spices on hand, which ever one it smells the closest to, add a healthy pinch and salt if it doesn’t taste salty already.
know your oils and use the right ones. Olive oil can handle some heat and is great for savory, grapeseed is almost flavorless. Canola has a distinct flavor that doesn’t go with everything.