ok! i love ur colors, characters and everything!
the shading is great, the anatomy, the poses, and lineart,,, its all pretty amazing, and im giving u full scores
but now ill tell u some tips on improvement (because this piece is amazing and i know u can do it better),
1. the lineart; the lineart uve done here is amazing! i reall love it, but the place uve gone wrong in this is the color of the lineart. the thickness and the amount of details is perfect, but the lineart's color! ruins it all...
what u should have done is,,, all the lines that do not belong to he character shouldve been colored a shade darker than what they are outlining (for eg, the sea lineart should have been only a shade darker than the sea)
and for the lineart of the characters they can be much darker, as they are the amain attention of the image,,,, u can choose an even dark color (like light brown maroon and change the layer settings to overlay or whatever) or u could lineart seperately, (skin outline 3-5 shades darker than skin, and the swimsuit outline 3-5 shades darker than swimsuit)
2. the back ground; i think u shouldve made the sky and the sand whiter
and the biggest tips here,,,, colors start merging on the horizon, so the sea and the sky will be only a few shades apart (the sky lighter, and the sea darker obviously lol)
3. the characters; the fat chick on the right isnt very good, her pose is slanted, her face is funny and the proportions are slightly off. but the other two are okay,,, but i still think the middle girl should be slightly taller, according to her head and torso
4. perspective; i think the girl who is sitting should look smaller, and slightly more back away, (according to the number of footsteps uve made.)
other than that, im really loving this piece (and i think its still a 5/5 stars lmao)
good luck! i hope to see improvement!!