Yes there are; but as this is a very complex subject, I would pass on the specific advises here. Although there are general meassures that can be taken to reduce EMI, there are also other methods highly dependent on the specifics of your circuits. Try to study the subject so you will understand the principles.
Just a few general subjects. There are many more...
-EMI filters.
-Relay contacts spark reduction methods.
-Relay coil damper diode.
-EMI shielding.
-Shieldered cables.
-Damper capacitors.
-etc.