Read the documentation. There are tools and features that will make some stuff a lot easier if you know about them.
Get familiar with creating your own symbols and footprints. No CAD program will have all the parts you need.
Don’t modify the libraries that come with KiCAD. Those changes will be lost when you update KiCAD. If you need to modify a part, create a new library and copy the part into it.
Double check footprints before you make the board. It’s no fun finding out the part doesn’t fit when you go to solder it.
Set the design rules to match the capabilities of the PCB manufacturer and run a design rule check before making the board. Don’t use the smallest traces and spaces they support if you don’t have to.