Intuition

From all the things I learned I think it's really hard to pick one lesson that stood out to me. Rather than that, I think I unconsciously made a synthesis of every piece of advice I received, and the result was that everything turns out best when you trust your intuitions.

Art is highly intuitive, the way you feel when you are creating ends up showing in the final piece, it's the vibe you get when you look at a painting, it's the reason why you might feel nostalgic when looking at a painting of a sunset, or why a large prairie might make you feel at peace. That to me is a truly successful artwork, one that makes you feel, and like I said earlier, it doesn't have to be a positive feeling, it just has to make you feel something.
That's where the artist's intuition comes in. If you don't trust your own intuition, how is the person looking at your art piece supposed to get an idea of what it's about? It goes beyond the simple meaning, that can be explained, but if your spectator doesn't feel what you were trying to transmit as soon as they settle their eyes on your artwork, there is nothing you can do about it.
In the end, what you create is purely yours, it came from your own hands and from your own mind, it's a part of you. So, if something feels wrong, it means it should be changed because if you don't like your own artwork, no one else will. Technical skills can be learned, anyone can be proficient at drawing, but if you don't have the ability to trust your gut and instead let others decide for you, you're just drawing, not making art.