There are a few ways of creating a model. You could:

1) Think af the model that you want to fold, then think of its base, which is a stick figure of its overall base. The stick figure, or tree, lets you see all the flaps and points that you need, at the place where they should be. Then, think of a folding sequence for it, and fold through the steps till you get to the base. Afterwards, you can fold to the figure you want.

2) When you are fumbling with a piece of paper, you might see a shape, resembling a type of animal. You try to make it into the animal, or at least its base.

3) You can also adapt a model someone else created. Note that slight modification (e.g., from a deer to a moose) does not mean it is your creation. If you change most of it, e.g. from a deer to an eagle, it is now your creation.

4) when you folded a model wrongly, it may instead take a shape of something else.