Put the lettuce in, move it around for a minute or two, then lift it out of the water and put it into a colander or sieve to drip. THEN let the water out of the sink. That way, any dirt or sand sinks to the bottom and goes down the drain instead of back into your lettuce. Sprinkle on the croutons and bacon bits. Mix with two spoons, digging down the sides of the bowl and lifting the lettuce up from the bottom of the bowl repeatedly so that you turn it over and over, mixing the dressing into the whole bowlful of lettuce.
Different dressings can be a really nice way to get variety, too.
Then you can decide whether you want to make a bigger bowlful, or change some of the ingredients first. Once the dressing is added, the lettuce will begin to wilt and should be eaten soon. When you're ready to eat your salad, pour on your dressing, mix it in, and it's ready to serve.