One of the most important skills when improving is knowing what needs to be improved, and then asking the right questions/finding the right solutions. When asking for advice, specific questions are almost always better than vague questions. Vague questions require vague answers, which probably won't be too helpful. For instance you say one of your problems is mixups. Mixups with approaches? Defense? Shield pressure? Recovery? I could try to try some vague answer which covers all those possibilities but it wouldn't be very helpful. Often a good specific question is something like: "as this character in this matchup in this situation, I am doing x and it is not working. What y should I do that will work?" If you can learn to break situations down to questions similar to this, it will serve you well and be a great skill. Good luck at improving!
Also I like your profile pic