1)Make sure the environment around the console is dust and dirt free. If your console is placed on a carpet, make sure you have the carpet has no dust. But still i don't recommend placing your console on a carpet because it blocks air ventilation and can increase the chance of overheating. I suggest if you want a dust free and cool console you place it on a clean flat surface such as a table or desk.
2)Every so often get a small powered hoover and clean the rear of the console and the fans. Doing this will keep your Xbox dust free for around about 2 weeks. Also hoovering the insides of your console will also make it much more cooler and more happy!
3)Don't place any objects near the Xbox console because they can also block air ventilation.
4)Wipe the console clean with a soft damp cloth every 2 weeks.
5)Don't play with the Xbox console for a long period of time. The more longer you play on it the more dust the fans bring into the Xbox.