Watch_Dogs PRO TIPS:
If you are escaping a gang or the cops and want an easy way out, jump in the water and swim to a boat. Escaping in the water is the easiest way to do it.
Second easiest way to do it is to get on the elevated train tracks with a vehicle or by catching a train. It will get you out of the search area fast. You can drive a motorcycle up the steps to a station platform.
Best skills to unlock are: blow up steam pipes, and disable helicopters. It would be hard to beat the game without them.
Best weapons: The full-auto shotgun chews through all but the heavy armor enemies, and the grenade launcher will take care of the heavies and blow up cars real nice.
Sometimes it's best to hide and wait if you can't get out of the area easily. However, some story missions will not let you do that.