Most police departments can't afford to go after such stuff, especially when they are made to spend so much of the budget on items such as biochemical suits and so on that just drain it. Of course the only real way they are going to deal with the gangs is to deal with the rapidly increasing poverty. When all the jobs are going abroad and the taxcuts go to the wealthy who just wall themselves off more and more from society. If they dealt with this crime, abortion, gangs all decrease substantially.
Neighbourhood watches are good practice in an area. Lights do work, but they can also have the opposite effect that they allow criminals to see easily. Cameras, fake or not work really well as do large signs pointing out security in the area works. You could even pay for a security guy to drive past every now and again and wouldn't be too expensive if you join up with the others. Dogs can work well if thats what they are train to do. A number of times the more peaceful dogs will be happy to have someone to play with so make sure you have them well trained. A burgular system and locking up the expensive tools work well should they get in. Perhaps shutters on all doors and windows.
Unfortantly beyond that theres not alot you can do.