Hey nice job!
I'm going to be really over critical so a lot of the stuff im going to say will be quite minor but.. the more you know! Im guessing you're going for a photo-realistic painting and you have really nice colour here but the inconsistency of detail is off putting. You have really defined edges around the eyes and smudges on the lips where there should be some hard edges with highlights. The eyes seem quite flat as they're mainly one colour and there needs to be some shading and highlights to really bring out the spherical form of the eye (the eye is always wet, moisture collects around the edge of the lower eye lid and around the tear ducts (keeping this in mind will help bring out the shape of the eye)). The whites of eye seem 'too white' and the stray hairs seem to be too thick and too black, most hairs like this seem to be engulfed by light and lose their colour strength or just lose their darkness because they're not collected like the main bulk of hair. Eyelashes are horrible to do but the eyelashes on the lower eyelids seem too short. Most of all I think that the bottom lip is too big and the skin could benefit from some pours, minor details to break up her skin and some alternative colour here and there to give the painting a more life like feeling as the skin doesn't have much texture. The forehead especially needs more work as it looks a bit rushed.
I do think you've done a good job regardless of all my criticism! Im super bored so I went all out with the critique but I do hope that I helped in some way.