I am accustomed to shooting with manual exposure cameras with interchangeable lenses. With my conventional cameras, both film and digital, I have full control. I can set exposure manually and can change lenses if I need to.
The Polaroid SX-70 is much more limited. It has a single built-in non-zoom lens. Exposure is automatic, with no ability to set exposure controls manually. The only control is a "Lighten/Darken" control. To use it, you have to shoot a photo, wait for it to develop, then set the control to a lighter or darker setting if the first shot came out too light or too dark. Keep in mind that the film is $2.50 per exposure! The autoexposure system in these cameras is primitive, as is the case with all cameras made in the 1970s. It assumes the scene is a middle tone (not light or dark); and gives an exposure that renders the scene as a middle-tone, even if the real subject is a bright white building or a black car! As I've gained experience, I am usually able to guess where to set the Lighten/Darken control based on what the scene looks like; but it is not as precise or consistent as a true manual camera is.
Another challenge is the film itself. It is a very high-contrast film. It can be impossible to maintain detail in both light and dark areas of a photo, and in some lighting situations it is just plain impossible to get a good photo. As I've gained more experience with the Polaroid, I have become able to look at a scene and decide if it is possible to get a usable Polaroid photograph of it. The high contrast also means that here is no "Exposure Latitude." With conventional films, exposure can be slightly off, and you can still get a usable image; and with digital cameras, you can often adjust the brightness of an imperfectly exposed image using software like Photoshop. With Polaroid, the exposure has to be precise; a difficult achievement with a camera that does not allow full manual control.
Even scenes with smooth, soft, shadowless light can look very contrasty on Polaroid film. The original Polaroid films, made before the old Polaroid Corporation went out of business in 2008, were more forgiving than the current Polaroid films. They had less contrast, more exposure latitude, more accurate color rendering, and were not prone to the streaks, spots, and other blemishes that often show up in photographs made with today's Polaroid films.