As a policeman

1. Communicate and coordinate all moves with all other policemen
2. Make sure that you pay attention to your remaining move. If you are on a spot which you can only have taxi and you have no taxi left, then you will be stuck, and your team will be short one policeman
3. Try to limit the robbers moves by surrounding him

As a robber

1. Try to keep your options open and not get yourself cornered
2. Be careful of moves which you will appear. Make sure on those moves you have many many options so that when you go invisible again, your next position is more unknown. Also if possible try to be as far away from the police when you go visible
3. Be careful of moves which give away your position while invisible. If you were close to a train station and then took a train then your position would be known
4. Use your mobility to escape quickly by train and boat