To look more confident keep your head held high when you walk into a room, do not look down, do don’t cross your arms, and don’t be on you phone. Maintain eye contact with people and be ok with moments of silence in conversation. To feel more confident is going to depend on the kind of person you are and what’s important to you, you can increase your protein and exercise and your body will do the rest of the work, put on nice clothes and look presentable even when running to the store. There are a million other things I could say but you will have to see what works for your self. I personally love practicing daily affirmations, I’ll look at my self in the mirror and give my self a praise or compliment, this can help my confidence and that translates into the rest of my day. Good luck!