Here is a list of simple things that you can do to stay on the right side of the law:
1) Drive a registered, insured, mechanically sound car, and have a valid driver's license. If you have expired tags or an expired license in many states the police can tow your car, and when they do they will begin to search around.
2) Don't smoke in your car, not just when you are on the way to deal, but ever. If you smoke in your car the scent will be all over, and it may fade away to you, but a K9 would pick it up quick. If a dog indicates you have drugs they can search everything. Every single part of the cannabis plant is illegal, seeds, stems, leaves, etc. If the feds wanted to fuck with you they could seize your car because of it.
3) Don't tell anyone about your grow. The more people that know, the more people that can turn on you to reduce their time inside.
4) Scent control, light control, heat control. If you can smell herb outside your grow area so can other people. If you have thousands of watts of bright light shining out of a bedroom in the middle of the night that could alert people. If you have the heat from the lights exhausting out of strange places it could look suspicious when the weather turns cold.
5) Don't ship directly to your grow. I ordered through a recommended website and added into the notes: "Please ship this discreetly". A week later the delivery truck showed up with my Growzilla reflector in original packaging. The only thing they shipped discreetly was a bag of Perlite. Fuckers!
6) DO NOT SPEAK TO THE POLICE WITHOUT AN ATTORNEY PRESENT. The Supreme Court decided in May or June that you aren't guaranteed your right to silence, you have to invoke your 5th amendment rights.
I'm going to post, or link to, a video that everyone should see. It is a law professor teaching his class about 5th amendment rights. His advice: Don't talk to the police, ever!
The funny thing is that he debates with a local police chief who also advises, Don't ever talk to the cops.
Video:
http://www.youtube.com/watch?v=i8z7NC5sgik