you are working it too fast....Slow down don't be concerned about getting it done right away.......
at this stage the paint should still be thin.....it seems like you are going too thick....
you can use thick paint but it is much more difficult to get the same results....you should be using it like its water color...
many coats of thin paint...slowly building up the layers to form the shapes and shadows...
what are you using? acrylic...?
use the grid for as long as necessary, the more you use it the more you will become accustomed to drawing...eventually you wont need it
of course this is all just my Opinion.
a good tip...
each color has a complementary color...they are
RED-GREEN
BLUE-ORANGE
PURPLE-YELLOW
take your background green and add a small amount of red to it, for shadows....
anytime you want to darken a color use its complementary color, do NOT use Black...
also DO NOT use Brown paint....if you need brown paint.... mixing equal amounts of any of the complementary colors will give you a brown...each one is different....experiment with it....this is a great way to get natural shadows....( the best way)
skin tones are best made with green&red
(and white)