Now I know there's also WD-40 Specialist High Performance Silicone Lubricant Spray which I wanna try out, I think this one will preform much better... let me know if you had any experience with this...
For now back on topic:
- Clean your window with the appropriate window cleaning solvent (you don't want to clean the blades to be dirty again on the next swipe)
- Check the rubber for cracks or damage, if there is any, its better to replace them.
- Use a soft towel or better a microfiber one, make it wet with some soft dish wash soap or your window washing soap (or use the WD-40, i dont have experience in this) and, gently remove the dirt from it, don't put to much pressure on it, this might damage your blades or rubber.
- Use some clean water after to remove the soap.