Hauling your camera and its accessories around can be quite distressing if you lack the proper way to carry it. A camera bag eliminates all the hassle. Acquiring one should be based on how much equipment you have. Shoulder bags are the go-to choice for most as they offer easy access to the camera. It is likely that you will buy filters, flashes and lenses down the road and having a safe place to keep these will matter. Besides, a bag will shelter your camera from dust and rain.
Holding on to your camera for the entire length of your photography session can be quite tiresome. If you need to use your hands, you are compelled to lay down your camera, which exposes it to damage and theft. This conundrum can be solved by investing in a utility strap. It will ensure the camera is close to you at all times. It is especially recommended since it eliminates all risk of you accidentally dropping your expensive DSLR.
Tripods are awkward to carry around, but their usefulness cannot be understated. It is a must have if you want to capture the most stead shots. You might not use it every time you are taking pictures, but it is very important that you have it with you. Aluminum tripods are good and sturdy, but also heavier to carry around. Carbon fibre ones are lighter, but also more expensive to buy.
These are the most important accessories to start out with. You might also want to think about lenses, density filters, flash diffusers and flashes as well if you want to make the most of your photography experience. The cumulative cost for a one-off purchase for all these can be quite high, so it makes sense to start out with what you will need for your kind of photography (nature, weddings, etc). The abundance of proprietary stores online should make it easier to find something that works with your needs, and budget.