1) Choose a background you like
2) Have good lighting. Natural lighting is the best typically!
3) Angle the camera a way you like. Try holding it above your eyes so it does not look like you have a double chin.
4) Try your best to have no glare.
5) Position your camera and hold it with a good grip!
Hope you found these tips helpful! But the most important thing about taking a picture is you being you and you liking it! Try adjusting to fit your expectations.