To improve a Goal tree, you need to examine the items in the tree. Using a technique similar to five why’s you can improve the goal tree.
Ask the question: why do you need it?
Example: garden shed
Let’s look at the goal of “Garden shed”. Why do I need a garden shed? Because I need to store my garden tools. Why do I need to store my tools? I want to have a clean garden. Why do I need to have a clean garden? To have a safe garden for the children to play.
Have a nice garden ← Have a safe garden for the children to play ← Have a clean garden ← Have a place to store my garden tools.
As you can see that by asking questions of your goals, you can find your reasons to do things. You can also see that it not necessary to have a Garden Shed, as long as you can satisfy these goals in another way.