You'd be best off working with a physio as everyone is different and needs to focus on different muscle groups where there may be weakness or imbalance. It's also extremely important to have someone show you how to do the exercises correctly, so you don't risk doing more harm that good (which may or may not be indicated by pain)
What's wrong with your knee(s)? Did you have surgery? What are you trying to achieve - sport, just getting around, being pain free etc?
Heel slides, static cycling with no resistance are good for ROM, but it depends why the ROM is poor - swelling, scar tissue, a fracture?