1. Not showcasing the relevant project / skills
Check what JD demands, and highlight the relevant capstone project that you may have done.
2. Answering a question confidently wrong
Interviewers are normally managers. Last thing they would want is to hire someone who can go wrong without knowing. There’s no time to inspect everyone’s work. Rather, it’s better to have someone who seeks help at every step rather than someone who does partially correct activity in silos. Hence as a best practice, keep adding ‘in my opinion’ or keep asking your doubts if certain things are not clear to you.
3. Not asking a question at the end
Any questions for me? -- No sir / ma'am
The questions you ask here, reflect that you have the capability to take charge of a pressure situation such as an interview and convert it into a conversation. Also most interviewers will drop you excellent advices for your career growth in general. So why not make use of it?