Most of the time a cold will get better on its own regardless of what you do! Your body's immune system is very good at taking care of these kinds of common infections.
That being said, as part of the body's fighting off the infection, you will feel more tired than usual. Therefore, it is important not to over do things. For example, vigorous exercise is not a good idea while you are fighting off a cold. Some people do find that they need extra sleep when they have a cold; at a minimum, you should try to take it easy. I would recommend that you focus on drinking plenty of liquids and eating nutritious meals.
Most of the time, the cold virus will run its course in 7-10 days. If, however, you find that the symptoms are still dragging on or worsening after that, or if you have high fevers, then you should go see your primary care doctor
to make sure that nothing else is going on. Sometimes, after a viral infection, you may be susceptible to other secondary infections, such as pneumonia
or sinusitis, and your doctor will be able to rule those out for you.