[speeder]

Pretty good advice already in this thread. Generally speaking, it's all about getting the calipers really clean where the pads slide in them and applying a very small amount, (tiny), of brake grease to the edges of the pads, (metal part), where they slide in the caliper. I also clean pins really well and replace them if they are galled at all. Sometimes a small file will smooth out burrs.

Basically, anything that causes friction where there is not supposed to be any is bad news. A tiny amount of brake grease on the rim of the piston never hurts, that is where the harmonic vibration that causes squealing occurs.

Something is definitely no bueno if you are hearing grinding. Take them apart immediately and investigate.