I spent this past summer at my internship doing camera renders in Illustrator. My tip is to observe, observe, observe, and replicate. You need to know how reflections work, how materials work, how lighting works...
Reading the tutorials will help you know tools, but you need to observe things in the real world to be able to implement them well.
I just found out about the pathfinder tool in illustrator while skimming through the Bberry tutorial. It really didn't explain any of the highlights/reflections in the chrome bezel, but now I hate myself for not knowing about pathfinder this summer and wasting time cutting and joining paths.
Oh, and I prefer Illustrator over PS because vectors scale much nicer, and with feathering effects and outer glows, you can basically get all of what you want from PS in Illustrator, just more editable. Of course, you could also combine the two and use smart objects in PS of your Il file.