How do I paint a sky?

-I am painting a tree on a canvas with acrylic paints and I want to know what kind of paint and how I would paint a sky behind it. Please help! Thanks:)First, make sure that if you paint the landscape you paint the sky before you paint the tree. The sky depends on each case. Sky can even be orange or very dark blue, it can be grey or sky blue or all of it together.

Look at your landscape and see what kind of sky is there. Start by painting white clouds if there are clouds, then can make some grey clouds and the add light blue on light spaces and dark on dark, make sure it'd interesting and live with color.
1. finger paint...

2. water colors

3. acrylic paints
I've seen things fly in all kind of directions and I need you to keep doing what my welcome doesn't because I believe you're a kind of colorful rocket.
Blend blue and white in together.
throw paint in the air. well if gravity pulls it down im not to blame