It is estimated that about 38% of all accidents in the workplace involve some form of manual handling activity, so are you lifting correctly?
First of all if you have to carry out any manual handling activity at work, you should be trained on it, and there should also be a risk assessment.
In the meantime, these safe lifting principles may help you:

THINK:
Is there any handling equipment available that can be used?
Do you have to lift it?
Can you lift it alone and safely?
PLAN:
Is the load light enough for you to lift it?
Is it stable?
Is it dangerous?
Does it have any sharp or protruding edges?
Will it block your vision?
Where is the best place to hold it?
Have you got the right footwear?
Are gloves required?
Is the route you are carrying it clear?
FEET:
Position your feet close to and facing the load
Keep your feet shoulder width apart
Put one foot in front of the other at a slight angle.
GRIP:
Grip the load securely close to the waist
Have the heaviest part of the load nearest the body.
POSTURE:
Bend the knees and avoid bending from the waist.
Keep your head up.
MOVE:
Move smoothly
Avoid twisting by using your feet to turn.
Put the load down, then slide it into position.
ALWAYS:
Push rather than pull
Keep your hands between waist and shoulder height.
Plan team lifts properly and communicate.
MAKE SURE YOU GET TRAINED