My photographer Karianne uses a Nikon D3000 with a Nikkor 50mm 1.8 lens and a professional blitz. When I take my pictures by myself I use a Canon 650D with a 50mm 1.8 lens. Before I used a system camera called Olympus Pen 1, where you just click and shoot. I missed being able to focus on the outfit, and the details - instead of having every single element in the background visible in the picture.
Portrait lenses like the 50mm are quite cheap (around 1000NOK) and give a much more professional look than the standard 18-55 mm lens you get in the package. I've also used a Nikon 85mm f1.2 and a Sigma 85mm f1.4 which provided stunning results. By now you're probably wondering what those 1.something numbers are. They indicate how much light the lens will allow into the camera. The lower the number (1.2) the better the lens is for taking pictures in bad lighting conditions.
The only problem with the 50 and 85mm is that you have to stand 5-10 meters away from the motif. Therefore my next purchase is a 35mm and a full format house (6D from Canon) The 35mm has more of a wide angle, which will enable me to take pictures inside my apartment - I've never been able to do that because I haven't got 5-10 meters to back up, to get everything in the picture. I hope this was helpful, don't hesitate to ask for more guides!