Here are some general tips to help you beat London Riots : The Game
1) Watch your molotovs: If they run low, find the blue molotov icon to replenish
2) Distract police: Police will try and put out fires within a certain range. So if you're looting a building, be sure to set some fires off around it to keep the fuzz off your back
3) Be systematic: Move through the level in a fasion which doesn't involve going back on yourself. This is an easy way to get caught by the police!
4) Find your own way: Clicking on a far away target and allowing the rioters to path find their way there is a bad idea. More often then not they'll walk straight into a copper. Manually make them take a safer route.
5) Fires first, buildings later: On levels with a large amount of burnable objects, you should focus your efforts on setting them all alight to distract the police. While they are running around putting them out, the city is yours to loot!