I have an Om10 which I bought in 1986 and it has been all around the world with me. I have taken more than thirty thousand pictures with it nowand the camera is still working perfectly after twenty years. The only problem with the model is that the shutter magnets need changing every ten years or so. Other than that the OM10 is almost fault-free. Everything on the camera is manual,and that is why the OM10 is so reliable.
When you wish to take a picture, you must set the aperture and focus for each shot. This becomes very easy with practice and you learn to do it automatically in about two seconds or so. When you switch on to take a picture, a small red light appears on the light meter scale in the viewfinder. Try to keep the red light at about 1/125 or 1/250 by turning the aperture ring on your lens (it does depend on lighting conditions and film speeds but those figures are the general rule). Then you must focus the picture by turning the lens. You ideally use the split circle in the centre of the viewfinder to focus perfectly, but you can focus 'by eye' when necessary. This is done by looking at the whole matt picture in the viewfinder if you have no reference for the split circle. For any pictures beyond about twenty feet, you can just set the lens to 'Infinity' to know that it is focussed.
As I said, the OM10 is all manual and the controls are basic and easy to interpret. To take a good picture you simply switch on, set the aperture and focus ( having wound the film on!) and then press the button. Have the camera serviced occasionally and keep the two light meter batteries fresh as the shutter will freeze shut when they are low. The camera takes a pair of No.357 watch/camera batteries which cost 35p each and they last me about a week when I'm away and I take about 30 rolls of film per week. Keep some spare batteries and remember that the magnets need changing every ten years when the shutter will again freeze shut to let you know.