I have been reading on the forums that a 1:1 ratio should be achieved between camera and photo.
Only if the digital camera you're 'scanning' with has a sensor the same size as the negative you're scanning. The D3300 has an APS-C sensor, so you don't want 1:1 magnification, but a little less than that.
You can do this with a bellows setup and any suitable lens mounted on that (e.g. an enlarger lens with manual aperture) like
@choiliefan suggests. Alternatively, you could take something like a 50/1.8 or so and use extension tubes, or you could use a dedicated macro lens.
For illumination, you could use a LED panel with a diffusor on top of it if the panel by itself isn't sufficiently diffuse. I often use milky plexiglass as a diffusor for various applications.
Positioning the camera and the film can be done either with some kind of rail system (search for a "slide duplicator"), a regular tripod or a copy stand (or an enlarger fashioned into a copy stand). There are all manner of ways to mount your film in a holder to keep it flat and stable, ranging from some cut cardboard to 3d printed gizmo's you can buy online.
What you choose depends mostly on your budget and how stringent your requirements are on image quality.