i saw u asked Solarsands to look at ur profile and review ur profile
i'm no solar but i can try and help
First of all, I would recommend making the lines smoother ( as in, making them not so wobbly / shaky ). It makes the art piece look messy. Next, I'd improve the shading ( I'm going to use your Undyne x Alphys picture as an example ). There should be some shading under the head, on the shoulders, at the start of Undyne's neck, both of their arms ( basically; where its necessary ).
To help with the shading, I'd recommend putting a light source somewhere in the picture ( I'd use
www.dummies.com/art-center/per… . I'm not trying to insult you with the website, it's just what I saw that actually described it well. )
Then I'd look at the anatomy. Its all over the place and isn't as good as it could be. I'd recommend looking up references for hands, faces, bodies, legs, arms and facial expressions.
( Lineart help -
sta.sh/01rwjgl11dc0( Shading help -
sta.sh/0p229a5xfionot the best, but It'll hopefully help.. )