Your new mattress represents a significant investment.  Your mattress will have more influence on how you feel than any other furniture item in your home.  Here are a few tips to help you get the most from your bed.
 
Most of today's mattresses are designed to be "no-flip" beds.  In other words, only ONE SIDE of the mattress is a sleeping surface; there is no need to "flip" the mattress over periodically.  However, it IS essential that you ROTATE the bedding to equalize wear – just swap the head and foot every couple of weeks for the first six months.  After that, simply rotate it 4-6 times annually.  This will greatly reduce the possibility of developing an excessive "body impression," especially if one partner is larger than the other.  If your new bed has a true "box spring" rather than a solid foundation, you may wish to rotate it as well.
 
Carefully read the manufacturer's warranty statement.  Warranties generally cover defects in materials and workmanship for 5-20 years depending on the bed and the manufacturer.  Your warranty may or may not be pro-rated; it may first have a period of full replacement followed by a pro-rated period later on.  Be aware that just as a new pair of shoes "break in," almost all beds will develop impressions as the padding "settles."  Different manufacturers have different standards for what constitutes a defect when it comes to impressions.  
 
Vaccuum your mattress regularly and be sure to protect your bedding investment with a quality mattress cover.  Today's covers are often lightweight, breathable and many are waterproof.  Bear in mind that stains or soil will invalidate your warranty; think of a good cover as excellent insurance.  If your mattress is equipped with handles, be aware that they are there only to help you turn or rotate the mattress.  Don't try to carry your mattress by the handles; you'll tear them out.