7 principles of good design feedback
Feedback is a key tool, that helps designers grow.
Good design feedback points out how to fix the issue, improve the result, and avoid making the same mistake in the future iterations.
Dig into the core of the problems in your decisions. If you don't get what the reviewer had in mind – ask more supporting questions until you understand why he gave such feedback and how you can apply it to your work.
Ask for the feedback yourself: in group chats, design communities. Write a message or tweet to more experienced designers and genuinely ask to comment on your work.
Feedback helps to shape good expectations with the client. Before seeking the solution to the problem, dive into the client's business, ask a lot, and clarify the details.
Before asking for feedback, give the reviewer more context. Ask to not only "look at the designs" but clarify what needs the most attention: typography, layout, colors, interactions. This will make the feedback more direct.
Don't be afraid of feedback and criticism. Remember that the number of mistakes only tells about the effort you put in to find solution to the problem and is not a characteristic of you as a person.