kicad is a good one. A bit of a learning curve. Cad models are downloadable from Mouser and Newark, although libraries are out there if you search. Drawing simple circuit diagrams is pretty simple. From design to production. And it's free!
I use Adobe Illustrator. I've handmade most of the pieces I use, although occasionally like the DPH42 I'm able to lift them from owners' manuals or what have you.