Be yourself. It's that simple. A good solid headshot speaks volumes to the agent. A good rule of thumb is to look as you would when going to an audition. If your hair is brunette in your headshot and you show up as a blonde, you're going to surprise everyone. You don't want to surprise the casting agent and waste their time. They will remember you, but in the wrong way. Heavy makeup, not recommended. You're not modeling for Victoria Secrets. Clean, natural makeup without lots of contouring, keep eyes to neutral tones, highlight your best features. Clothes simple, v-neck t-shirts, solid color shirts, blouses, dresses work best, pick a color that goes with your eyes and skin tone. Backgrounds not too many distracting details if you shoot outdoors, or clean studio shot is always a winner. And above all, let your personality shine through and you'll get a call back every time.