Since the question about how to begin with crease patterns (CPs) arises that often I decided to create a sticky post about it.
First of all, what exactly is a CP?
A CP is like the name indicates a drawn pattern of creases, that shows the main creases you need to create a (flat foldable) base from where on you need to add more details until you end up with the finished model.
Sometimes only one half of a symmetrical CP is shown and the other half shows how to get some important reference points.
To fold after CPs you need a lot of patience and experience. If you're a beginner with Origami first learn to fold after diagrams before starting with CPs.
When beginning with crease patterns make sure to begin with the easy ones. Like with everything else only praxis can make you better and sometimes folding something else and then trying again will get you further than trying the same model again and again without success.
A special case of CPs are boxpleated ones. You can identify them at once by the large amount of fan-like horizontal and vertical creases only divided by 45° angled diagonals. When beginning with this kind of CPs first fold in half along the symmetrie line and continue with making waterbomb bases on the 45° lines. After sinking everything in and out you will need to open out parts of the CP to add the remaining creases in the right directions.
Topics about CPs on this Forum that contain useful informations can be found here
The best website guides when beginning with CPs can be found here
to find a lot of boxpleated CPs.
Useful programs for creating and solving CPs are Robert J. Langs Treemaker
and Reference Finder
that can be downloaded from his website
for informations on vertex assigned CPs.