Use the portrait function of your phone (if it has it) and use the main camera for better quality. Hold your camera between you and a light source, and turn your body a bit away from the camera wile keeping your head towards it for a more natural look. As others said, the result looks best if you take the picture from further away and then crop the result. I usually try to crop out my arm as well so you can’t clearly tell I made the picture myself. Take some pictures while playing around with the angle a bit and look at the results, then take more pictures with the best looking angle and repeat until you’re satisfied with the result.
It takes around an hour for me to get a good picture usually because you need to play around a bit with different angles and faces but the result is often really good. I hate taking pictures of myself but putting in the effort once every while is worth it for me.
A picture in which you smile usually does better on dating apps because it makes you seem more approachable, but a more neutral expression is also fine
Awesome!