Again, your skills are very impressive, and the color jobs are even more impressive than that. However, the critique which no one else is willing to give (please don't take it to heart)-
She looks like a pregnant cabbage patch kid with the eyes of Smeagol from Lord of the Rings.
I'm sure this wasn't the look you were going for, but thats what it looks like to me. But part of a good, honest critique is offering advice or suggestions also. With that said, I think doing these things will keep this from happening again if you so desire-
1.) She looks pregnant or like she has round stomach.
To correct this, simply draw her more toned. If you meant for it to appear that her back is arched in this picture and perhaps thats why her stomach sticks out, then that look can still effectively be achieved by creating contour on her stomach. How you draw the line of her stomach, her ribcage, etc., will change the look to what you want/need.
2.) The expression on her face is up in the air. I can't tell whether shes sad, happy, or ready to laugh. She looks like she might be sick with how you drew the lips, eyebrows, and the plumpness of her cheeks, they look almost swollen. These parts of the face are very key to the expression on a character's face and if drawn in an ambigious way can mislead the viewer. While we know this is a tickling picture, if the hands tickling her were gone there would be no way for anyone else to tell what this picture is about. Alot of different things could come time mind.
So I'd suggest this-
Don't over-express the character. I feel you put TOO much expression or emphasis on her face that it takes away from the picture. So simply perhaps draw her cheeks less plump, don't curve her bottom eyelids so much (thats adds to the puffyness of the cheeks), try drawing the lips in such a way that the expression is clear. While her nose and lips give her a cute mumpsckin(sp?) look and give her a cute 'pouting' sort of look, it leaves her expression undeterminable.
You overexagerated her tears. While some people may very well cry when being tickled, they won't be flowing a river, even in anime (unless its one of those cute SD Chibi scenes which are supposed to look like that). So perhaps next time there are tears, you might not draw them so pronounced.
Her eyebrows make her look confused. If she is trying to hold back the laughter (which is what I'm assuming you were going for), her eyebrows wouldn't look so loose. They would be slighted or greatly tightened depending on the level/method of tickling or ticklishness on the part of the ticklee.
I hope this helps. 🙂