CHECK OUT THESE GREAT TIPS WE FOUND ON THE CARPET AND RUG INSTITUTE'S BLOG:
1. Not Change the Bag: When your bag or bin (for bagless vacuums) is 1/2 full, suction power is reduced by at least 50%. This means you need more strokes over an area to clean it and it is making the motor work harder. It is best to change the bag or empty the bin when 1/3 to 1/2 full.
2. Use the Brush on Bare Floors: A powered brush is critical for deep-cleaning carpets. But the revolving bristles can scatter debris while scratching the finish on hardwood and the plastic wear layer on laminate floors.
3. Vacuum Hard, Sharp Objects: Nails, screws, coins and even paper clips can rip bags and damage the machine. Either pick them up or sweep them up with a broom before vacuuming.
4. Suck Up Water or Wet Messes: Had a flood? Avoid the risk of electrocution by leaving your upright or canister in the closet. Use a wet-dry vacuum with a ground-fault interrupter for standing water or even damp debris.
5. Toss It When It Loses Suction: Full bags are not the only reason a vacuum's suction can suffer. Check the hose to see if it is clogged. If the hose is clear, check the filters found on bagged and bagless vacuums. Also, if the brush roll barely turns, check it and the drive belt for tangled string or hair.
6. Assume the Motor has Blown: Many models have a thermal switch that cuts current to the motor if it begins to overheat. If your vacuum shuts off during use, check for a full bag or bin or a dirty filter. The switch should reset itself, though some models have a reset button for that purpose.
SOURCE: http://www.carpet-and-rug-institute-blog.com/