Hi! If you are a user with high IT knowledge, I highly recommended the freeCAD ( http://www.freecadweb.org/ )
other wise there is another online solution … This is beta, but a really good initiative. This is the https://www.onshape.com/
But my personal favourite is the Autodesk Inventor
If you’re doing 2D CAD, check out QCad: http://qcad.org/en/ It didn’t take me long to learn and I was able to design all the parts for a laser-cut 3D printer with it. The full version is $33 and the trial version is full-featured, but shuts down some tooling after 15 minutes each time you run it. You can just re-start to get the features back, but it’s so cheap, that’s hardly worth it. It has a CAM add-on, but I’ve not played with it. It’ll also run on Mac/PC/Linux and I’ve swapped easily between Mac and PC versions.
For 3D, I’ve been very impressed with OnShape, both as a product and with the way features are released so frequently and explained well on their YouTube channel.