Go out and use it a bit to familiarise with the controls
Rough read as much of the manual as patience will allow - it is good and comprehensive if rather terse
Use the camera more thoroughly
Pick sections of the manual and try and fully understand them it will get easier as you go over the hump of familiarity
Custom modes are great, perhaps the best way to start using them is to set up the camera for a particular shooting purpose and then save that setting - you can custom name them to help remember waht they do. My three main modes at "Good light" - in colour and where conditions are good. "Quick" where I am in a hurry or the light is less than optimal (higher ISO allowed). Also B&W as I quite like B&W imaging.
Read a good introductory book on camera technique - the GR rewards those who use it with some thought.
Analyse where an image went wrong (if it did) or how it could have been better caught if not on song.
Ask questions, someone will help.
Enjoy the GR it is just a little more than "another camera". You are well on the way to being an enthusiast.
