Two things..

1.) Take the photos of yourself, while watching yourself on the computer. Start with your computer video/ camera.. make sure the lighting in the space is good.. and start taking photos of yourself.. while you watch yourself on the computer screen..I would not use a phone.

2.) Imagining someone you think is very beautiful while you are taking photos can help. When I was younger I would always think about Audrey Hepburn ..I would think about her facial expressions, and how she would pose for the camera.. And over time, I become more graceful and elegant in front of the camera. I've had other people take this advice when I've taken photos for them,and it has helped them as well.