In simple terms criticism means judging something for the merits and faults. In honest opinion, criticism brings out the best version of yourself. It is up to you in which way you want to react to criticism. Some people let it hurt their feelings while others strive to make the best out of it.
Criticism just like anything can be good or bad or both. In any action or any product, there will be bad and good sides. You are human, and you should know you can never please everyone. For some people, your work or character might be perfect while for some it would not even be considered good. So, the whole thing comes down to you.
You are your best critic. You would know what you want out of yourself, so you would know what you need to improve. If you want to, you should want to be the best version of yourself, but definitely not for competing with someone. Competing with anyone is exhausting and not fruitful.
If you have a mentor, or consider someone your well-wisher, you should listen to them closely. You should think if you also agree with what they are saying. If you disagree with them, think about what they said after a while. They might see what you need to improve before you do.
The reason it is best to listen to well-wishers and mentors other than just anyone is because there will always be people who would want to put you down. They would sometimes do it because they are internally not liking your progress or some other petty agenda. Listening to them is your choice. If you are confident, and you are sure it would not get to you, you can listen to what they have to say and think if you really need to improve that or not.
Making the best out of criticism does not mean letting bad criticism get to you. If you hear harsh words, you should know better to not let it get to you. If it gets to you, you would not give yourself time to think if it needs improvement or not because you would already be feeling gloomy about what you heard. It is very important for your self-growth to listen and then think instead of jumping to conclusions.
It is also important for you to be happy and pleased with yourself when you think you are doing great. The more you feel joy, the better your work becomes. A good compliment for all the hard work you put through makes your day, but initially when you start the road to improvement, you may not hear a lot of compliments. So, it is extremely important for you to see how far you have come on your road to improvement. Set milestones and keep checking your growth. Wishing you a successful journey where you make the most out of criticism.