Stay out of trouble

If you are going to get "dirty money" always remember the laws and try not to do something stupid that will attract the attention of authorities, thus get you caught. Always expect to get pulled over and be ready to handle the situation. You need a fool proof way of keeping merchandise out of a cops site and smell. If they smell or see something, they automatically have reasonable suspicion, thus the car search begins.
If you happen to be in the wrong place at the wrong time, you may also get caught. Try to avoid people that spontaneously just get up and commit crimes. These people will cause you jail time and cost you money. Trust is a big thing. You may not know who to trust. But I'm sure you would be able to tell which are your true friends and which are not.
Lastly, don't forget about the grand pre-paid phone. Use a fake name for your account and always pay in cash. The best deal is setting up a text bundle for a fixed price each month. Most phones will even allow you to block all incoming and outgoing calls. Remember that your phone from your contract has a lot of personal information associated with it. If you were ever under investigation they can pull up your phone records and find out everything.
One other thing is, stay close to people you know. Don't mess with people who are friends of so and so. The farther you stray from known connections, the more likely you are to get caught. Not only are you at risk of getting caught, you are at risk of getting robbed by an unknown contact.