I'd work on the anatomy first.  The breasts are much too high.  The arms seem a little short and very rigid.  I'd also suggest using more contrast on the colors used on the skin.  And since shes clothed and in water, maybe a little wet effect using the darker red up to maybe knee-level.  The dithering also looks out of place as it is only used on the character and even then it hasn't touched the hair.

I would personally lower the wetness a little bit.  I'm not sure if you would really want to dither a piece this size, but at least the dithering is now consistent.  The arms, however, remain stiff; and it'd be nice to see a little more detail on her stomach.  The breasts look better, but could still use a little work.  I wouldn't give her such defined cleavage.

I believe he means how the wetness of her trousers goes so high.

Any better?

Also, should I keep the change in the lips or no?

I say lower the wetness still and add a darker yellow colorr plus a darker skin color, also add more contrast on the skin.