My washing machine washes, not exactly clean all the time but in addition, it does not spin all of the water out. Help!

Please provide more information before I can advice you :

-Since when is this going on?
-Did it develop over time, or did it start suddenly?
-What do you mean with "My washing machine washes, not exactly clean all the time"?
-Before the spin cycle starts : is the water pumped out of the drum completely?
-Immediately after spinning is the pump still trying to remove any remaining water?
-If the drum spins, is that at the usual speed?
-Anything else different than previously?

Thanks!