1. Make sure it's in a well-ventilated area. You'll want several inches of space on all sides, and I would recommend at least 6 inches clearance for the back where the fan is. The more ventilation, the better.

2. Don't keep it on a carpet. Ever. Under any circumstances.

3. If it is located in an area that regularly accumulates dust (or if you have household pets like cats or dogs), you may want to regularly vacuum it.

4. Although there is no reliable evidence to suggest that it is better to place the 360 horizontally, I'd recommend it anyway, where possible: it's just way less likely to be toppled that way.

5. Whichever way to choose to place it, keep it on a stable horizontal surface.

Firstly to prevent the RROD from occuring place your console in a well ventilated area, away from any objects that produce heat like Plasma / LCD TVs, heaters, etc. Also try to keep the area around your console dust free. Do not place the Xbox 360 or the power supply on a bed or on carpet as this prevents air getting to the console and power supply. Also do not use a Xbox 360 fan attachment as these can cause the RROD and scorch your consoles power supply unit, they are a waste of time and money.