need help or info on repairing my 1990 ford lincoln power windows?

can't afford to take my lincoln continental into shop,so need all the info I can get.Ok,the problem is with the power windows on both sides.One side will go down smooth,but comes up rough while the work fine.The ones in the back quit working completely.Where do begin? The wiring,the motor,the window trackings or guides?? Please help asap! (it's a 1990 Ford Lincoln Continental) thanks