Like Marin, I have a permanent set (2) of spring lines attached in my slip. Since I single hand 99% of the time, when I enter the slip I step on to the dock and put the loop end over the boat cleat, amidships. I now know that my boat is positioned fore & aft in exactly the right spot. The rest is simply a matter of centering the bow and tieing down the boat. I do, however, carry a full set of lines on board within easy reach.
When company is aboard, they always want to help out and this bugs me to no end. I politely tell them that I have "a routine" that I follow and would they just have a seat until we are underway. It seems that every time I violate this rule, allowing for some visitor help, something is always missed, and as captain, it's entirely my fault.
Walt