Unless your boat is unusually heavy or will be subjected to severe conditions, a bow line, stern line, and two spring lines are recommended. Spring lines keep the boat snugly near the dock by preventing it from moving fore or aft, while allowing for the rise and fall of the tide. Of course, if your permanent slip has outboard pilings as well, you'll need an additional bow and stern line. These diagrams show two common docking arrangements. If you're away from the boat much of the time, lines should be longer to allow for high water from storms and tides.
Short lines are a prime cause of damage.
Also, put the eye end of your dock lines around the cleat, bitt, etc. Conversely, if you spend most of your time aboard, put the eye around the fitting or piling ashore and adjust from the boat. Although inevitable, it's not uncontrollable. In a permanent docking arrangement, the chafe problem is most chronic. First, chafeproof your boat as you would childproof your home.