>>3279592>took photography in college>already mastered thatYou’ve mastered nothing, or you wouldn’t have bought an entry-level DSLR THEN asked /p/ about it.
Here are some tips:
Buy a prime lens. I like the Nikon 50mm 1:1.8G - it’s relatively cheap in with DX format it’s about equivalent to an 80mm lens on full-frame. Great portrait lens.
Buy Photoshop and Lightroom and shoot in RAW (NEF) - learn how to edit your photos
The kit lenses that come with Nikons usually suck