Weight management via diet, lifestyle and exercise modification can result in a great deal of relief from OA, in fact studies have shows that a loss of just 5kg can provide significant improvements. This is thought to be due to both reduced mechanical load through joints (due to lower body weight) and reduced inflammatory cells circulating in the blood (fat cells release inflammatory cells to reducing fat reduces the inflammation). If you are a smoker, or drink alcohol that would also be a big one to try to cut out to help reduce symptoms.
Aside from that, as mentioned previously, physiotherapy, myotherapy or other manual therapy can help, provided the practitioner you see has a modern understanding of OA and pain science. Your therapist should help you with addressing biomechanical factors but also realise that other psychosocial factors may be contriburing to your condition, such as your beliefs, or what you have been told in the past about the state of your body.
Exercise should focus on strength training, to ensure your muscles can better support your joints.