The crips may start off in a very unstrategic location, but they do receive the benefits of a large drug trade in their area which pays for all of their cheaper improvements.
The crips first objective should be to defend what they have. Once you have 2-3 units in each city quickl expand using Looters into the slums to your southwest. They are unclaimed and can give you a quick boost in resources. Once you have done that, clear the civilians in the local area out. They are much easier targets than the police strongholds. Once you have obtained superiority in your area, instead of confronting the police, you may wish to consider attacking a rival gang and taking their territory from them. From there, it's up to you to pick out the weakest targets.