What do i need to start a great photography journey?

So far all I have is a Nikon D SLR… Thanks

Basically you need a journey and to prepare cards, batteries, lenses

You're already prepared.

You have all the equipment you need to start. You now need the time, patience & effort to hone your knowledge & skills.

Explore all you can - learn the basics of photography - exposure, lighting, composition. Learn to 'drive' the camera - place the exposure where YOU want it, rather than the camera deciding. Begin to develop a style, and/or a favourite genre.

As you move towards a particular type of photography (landscape, wildlife, street, portraiture) you will add to your lens collection, maybe even add supplementary lighting, a tripod, a couple of filters.

As your portfolio grows, try to get some meaningful feedback (ie not from friends/family, who will be biased) on how your images look. Joining a camera or photography club is a great idea.

Inspiration, an open mind, and the ability to see a great picture when it is in front of your eyes.

You should practice with your camera and outfit in many different situations before your journey.

Technically? Probably a zoom lens longer than the 'kit zoom' of 18 to 55mm. Possibly a wide-angle zoom, though good ones are expensive. A good camera bag to hold those things. Possibly a tripod. Probably a flash-gun (speedlight) and the means to hold it off the camera (cable or radio control), but do try to take most interiors without flash for better atmosphere. A large-capacity camera memory card definitely. Possibly a spare battery. If going outside your country adaptors for the electrical plugs in various countries. Check if your charger can work on 220 volts - Americans sometimes experience an loud explosive moment when plugging 110 volt items into 220 volts.