Hi,
maybe two years ago I tried to model a smooth looking parametric hook, but failed pretty much (because I couldn't find a way to place sketches on the right places). Now using Part Design next, the job can be done within 15 minutes. I like the new Part Design! The new tools like Datum Planes are a huge step forward for FreeCAD.
If you want to see how I designed the hook, follow the link to youtube (be aware, the video is in german):
Edit: I recorded the video again and tried to use your advices. Many thanks to you, I never ever saw a forum which is as helpful than this one!