Frist steps in CAD, part library?

I’m currently doing my first steps with CAD (namely freecad, but I want to try a few different programs). Now one thing, I’d find handy is not to do standard things from scratch all the time. E.g. parametric enclosures with rounded corners, stand-offs for common screw sizes, cut outs for nuts or the different USB sockets, slots for LEDs, clip-in’s for circuit boards, dove tails and the such. I figure there must be a part library, for all that. The closest thing I found was customizable enclosures on thingiverse. But there should be much much more. The questions is, where do I find such a library?

I’m just starting out, so sorry if it’s obvious. Before someone says “just google it”, I’m looking for recommendations for GOOD libraries with well-made parts, you can trust. I’d be grateful if you guys could point me in the right direction.

Bolts!

http://www.bolts-library.org/en/index.html

Wow, that’s pretty cool for Nuts and Bolts and bearings. I like the interface. Any more stuff (connectors, hinges, snap-in’s?).

It may not be a library, but McMaster-Carr has tons of CAD models. Digikey has quite a few, as does Fastenal. Then there’s 3DContentCentral, Cadenas (which may or may not be available to the public), and GrabCad (which anybody can upload to, so it’s not completely reliable).