try checking the battery
A loose belt. Most likely the alternator belt, if it doesn't squeal when you make a sharp turn.
That depends on how, when and where it is squealing. For example, if the brakes squeal when applied, the brake pads are probably worn down. A squeal from the engine compartment whenever the engine is running could be a loose serpentine belt (especially if the squeal changes a little when you rev the engine).
You Dont Grease It Up enough
It can be several things, either by themselves, or in combination. 1) the belt has dried up and isn't as grippy any more. This causes it to slip and squeal. There are sprays available to restore grip on belts which might help. 2) the belt has stretched a little, which causes it to slip and squeal. Retension, usually by adjusting the alternator position and it should be OK. 3) one of the auxilliaries(alternator, power steering pump, water pump) is about to seize. If it's harder to rotate the belt will slip and squeal.
Pads worn out. Dust between pad and rotor. Leading edge of pad has 'feathered' and needs filing off. Pads fitted without anti-squeal shims.
A loose, cracked or dry belt.
A loose belt that becomes more noticeable at cold temperatures.
bad brakes.
Sounds like it needs some lubrication. Try applying some graphite powder.
power steering
I actually was suprised my grand prix was squealing and it was the alternator. I got it replaced and it has stopped.
Could be the power steering pump.