So, here are some observations and tips to get better results from old cameras:
None of the big camera manufacturers and few of the small ones made any cameras incapable of making technically superb photographs. The folding cameras, box cameras and plastic point-and-shoots - even with the simplest lenses and no options for shutter, aperture or focus adjustments - were and remain capable of producing sharp pictures with pleasing tonalities. To be sure, there are real differences in features and capabilities among different types and formats, but that only means that the photographer needs to work with the camera long enough to learn to operate within the parameters of any given camera. Claims which denigrate quality control in the factories of Kodak, Ansco or Argus can be safely ignored as they are always without evidence or documentation.
Old mechanical shutters, even in very high quality cameras will become sluggish with a build up of dust and congealed lubricants. Often, a couple drops of a solvent such as Ronsonal is enough to get them working more smoothly. What if you try that and the one-second or half-second speeds still do not work perfectly? Don't let perfection become the enemy of good enough.
Box cameras often have simple shutters which remain reliably consistent for years, but a speed as low as 1/25 second is common and can easily lead to blurry pictures if the camera is not securely braced at the time of exposure. The fixed apertures in such cameras are quite small in order to insure sharp focus over a wide range of distances. However, the focal length of the majority is close to 90mm, so with a camera like the popular Brownie Hawkeye Flash the photographer should not get closer to the subject than eight feet. There are a few exceptions like my little Ansco Panda which let me get sharp results at six feet. Simple push-on accessory lenses such as the No.13 for the Hawkeye Flash allow close-up portraits at 3.5 feet.
Old folding cameras with accordion-like bellows are very likely to have tiny pinholes that will ruin pictures. Such pinholes are usually easily repaired with a dab of black fabric paint, but first they must be found. Take the back off of your folder, point it at a very strong light source like the Sun and wiggle it around to spot the pinholes in the creases and corners of the bellows. Then, take the camera into your bathroom, turn out the lights and run a small LED flashlight along each fold and crease inside and out to find any remaining holes. The other common source of light leaks in the old folders and box cameras are the ruby windows in the back which allow viewing of the frame numbers on the film backing. Keep the ruby windows covered with a bit of black tape except when winding on the film, and do not allow illumination of the window by direct sunlight. Some modern roll films like Kodak's otherwise marvelous TMAX have very low contrast numerals on the backing paper which render them nearly invisible through ruby windows. Save those films for use in cameras with automatic frame advances like the Yashica-Mat or the Mamiya C330.
American and German camera makers relied on good-fitting, baffled backs to avoid light leaks from that source. However, they often needed to add a strip of light seal fabric in the hinge area to keep light from getting into places it should not go. Worn hinge seals are easily replaced in such cameras. The Japanese made extraordinarily well-crafted 35mm cameras in the post-war years in which they perversely installed foam light seal strips all around the perimeter of the camera backs which inevitably turns to awful goo in a decade or so. Luckily, it is not difficult to cut replacement light seal strips from cheap foam sheets which cost only a buck or two at you local big box store. Another good source of foam-like material for light seals is a thin computer mouse pad; I just bought one from Staples that my mouse is comfortably resting on, but will likely end up in a couple of my old cameras one day.
So, get out there and make some pictures with those old film cameras! And, cultivate the thought that whatever camera you are using, be it ever so humble, is fully capable of making stupendous images. You will get what you expect.