I don’t think what I have to say will ever be replaced as probably the most important advice I can give to any new designer or current designer.
“Never get complacent, Never stop learning, Never stop practising”
One of the biggest mistakes I did was, I stopped learning and expanding my skill set. This mistake made me stagnant and got me left behind in terms of trends and new techniques that appear in the design industry.
Even now this mistake affects me until today. I am still trying to catch up on my technical skills, while I maintain my Design Leadership and Management skills. Do not stop learning new skills in your field. It takes a lot of hard work to rise out of it.