There are a few ways to stop squeaking windshield wipers on a vehicle. The first and easiest step is to clean the wiper blades. There needs to be a little lubricant on the wipers to prevent squeaking and dirt on the blade will cause this. Your windshield wiper flood should have some amount of lubricant in it so you can take a rag and put a little windshield wiper fluid on the rag then clean the windshield wipers. Another good product to use is plexiglass cleaner. If your wipers are old you will need to replace them as this can cause squeaking as well.
The only thing you should wipe or clean the rubber portion of the blades with is alcohol.
Secondly, depending on the quality of the blades you currently have on the car and the climate you live in, they should be changed every 6 months anyway. They are very inexpensive and any auto parts store can remove and install them for you at no charge. ( Discount Auto, Pep Boys, Autozone etc )
Lastly, wipe your windshield clean with alcohol as well to remove any road or pollution residue that may be on it .