If you want to summon or change something in your dream, you stretch your hand before you and cover the object. focus on your hand, and say/think of what you want to see.
when you move your hand away, you are most likely to get what you wanted
I’ve got to second what Ev has said. It works for me sometimes as well. Also, waving my hand like a Jedi master seems to work as well.
For physically controlling things like the weather, or levitating objects,
palm outward, fingers slightly bent, place your focus about 1 inch in front of the palm.
Great method Ev! Whenever I wanted to change something, I always looked away, visualized whatever I wanted to see, and then looked back. Usually this method worked fine, but it also altered some other things. So your methods seems much more specific and thus more efficient. Thx for sharing it