I still can't say for sure which is my preferred subject to shoot or which subject suits my shooting style. This is important as you will know what lens to upgrade to. For instance if you are a keen on sceneries you will do good to invest in a AF-S DX 12-24mm f/4G IF-ED and if you are a macro shooter, a AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED.
Anyway, digressions aside, there must come a time when you can say to yourself that you've reached a certain milestone in your phototaking journey. For me this first step was reached yesterday when I joined a band of photographers to shoot a Singapore Fashion Festival show at Civic Plaza. Though I learn something new from every subject I've shot, I believe I've gained a tremendous amount of experience from this shoot, whether it is by observing the professional photographers or by taking note of my mistakes. I don't know what the next milestone will be but I am looking forward to learning more. Remember, it is always the photographer, not the camera that is in charge.
p.s. Though of course I am still aiming for a AF-S VR 70-200mm f/2.8G IF-ED and a SB-800 after my first paycheck. :P