My suggestion has always been that one should decide on a sample/typical project which is reasonably simple, then draw it up in a tool which is suited for it, then decide on materials and tooling and work up toolpaths and get a 3D preview — if you are successful doing this, and it’s an approach to creating which you enjoy, then a machine is probably a good fit.
Which tool you use for drawing/CAD (Computer Aided Design) depends on what sort of work you wish to do and how you wish to approach it.
Most folks use Carbide Create as @Spyd suggested:
it’s included with the machine, and well-suited to most projects which folks use the machines for and how most folks work. I wrote up a very basic bit on it at:
Note though that one can just draw stuff physically, photograph it or scan it, then trace it, either by hand or automatically:
Some folks use 3D CAD/CAM such as Autodesk Fusion 360 — we offer Alibre Atom3D:
If you’ll let us know what sort of things you want to make and how you wish to approach it we will do our best to advise.