My approach in fusion is to start with the most complex profile shape and create a sketch on that dimension and then just keep removing or adding features using sketches on the other axes.

For example for your radio holder I would do a top down sketch with 2 circles connected with 2 lines, times 2 inset from that, then add a couple cuts to get the C shape. Extrude that and then do a separate extrude of the entire outline (without cuts) and set the extrude offset to the height of the model so that the new body ends up at the bottom of the previous extrusion - and more set to join if they’re touching so it automatically merges them.

I hope that gives some idea on how to build up shapes - I haven’t really used any tutorials but just kind of wing it by trying to make my first sketch of a part from an angle where that sketch can take care of as much complexity as possible so the finishing touches can be simpler. (Ie, if you made that orange part from the side, the initial sketch would be a square and you would have to do a lot more operations to cut off material)