There are a lot of rumors and myths about xbox repair online. Type xbox repair into youtube and you will be buried by a mountain of bad advice.
The Towel Myth
The Myth: Wrap your power supply in a towel and leave your xbox running for several hours to fix issues. The idea is that this causes it to over heat to such a degree that the solder will melt and reflow. This is supposed to fix any bad solder joints.
The Truth: This will cause your supply to over heat but not enough to cause the solder to reflow over the joints correctly. However it will get hot enough to damage the other components. They are not designed for such high temperatures. The heat will cause latent damage that may not cause an immediate failure but will with time. This myth has also been retold but with wrapping the towel around the xbox itself! Again this wil cause more damage than it will fix
The Angle Myth
The Myth: Tilt your console over at 45 degrees, always position your power supply vertically. Can only assume that these are supposed to help in keeping things cool.
The Truth: Making sure that your xbox console has adequate airflow and ventilation will do more to help than standing it at any crazy angle. Same goes for your electrical supply, keep it off the carpet (that just helps things heat up), raise it up with bottle caps so that air can flow underneath it.
There are excellent guides available that have clear instructions, pictures and videos that will guide you through your repair. If the repair is beyond your technical comfort level, seek out a reputable company, not some grainy shaky youtube video
If you want to learn more about Xbox 360 repair tips, check out http://www.fixyourxbox360.blogspot.com