One important thing that Katie E touched on, is temperature drop when you add your food. The more mass you have to hold the heat, the less of a temperature drop you'll experience when you add your food, and the better-quality your fried food will be. Use the heaviest, biggest pot you have (a Dutch Oven is great for this), and as much oil as is SAFE to use (allow for displacement and bubbling). Restaurant fried foods are great, because those fryers hold between 5 and 10 GALLONS of oil, and are controlled by a thermostat.
I prefer to use my counter-top model, as it has a thermostat. Otherwise, Dutch Oven and a deep-fat thermometer are used.