Perhaps I can help....as it is easier than you think. There are just a few things to keep in mind....
They will be a guide for a successful bird even if you do it all in the same color with no regard for light or dark areas.
you must not only think of the colors but the values... See if you can define the lightest and darkest areas of this bird.
Sometimes it helps if you can copy your bird in black and white... Then it is very easy to see.
Then I just fill in between the light and dark with the between shades.... Usually with one and then working back over it with a couple more shades close in
It really defines the edges as I stitch into it as I progress and it makes it very easy to cut out.
If I have omitted something or am unclear, I need you to ask questions so I can get it all right...