Hey bro's figured id post this since there is not much talk of it and because if there is it is vague.

Never sell to anyone.
This allows you to be considered a dealer in local law enforcements eyes and now instead of just possesion you are facing felony charges of trafficking and dealing.
Never trust anyone.
Just because you sell to your best fried does not mean they wont sell you out. Someone always has something to loose. It could be they were arrested or they face jail time for a lesser crime, if you sell to them you give them an option out if they can prove that you are a dealer which with just one simple favor to them they can. DO NOT SELL TO ANYONE!
Never sign for anything!
If you sign for anything this is admitting that you ordered it. Even if law enforcement has recoreders of who a dealer sent items to there is no way to prove it. Even with tracking it is extremely hard to prove without a signature. Things get lost in the mail all the time. I even confirmed this with my local post guy who said that the way they marked packages sometimes even confused him.
Never let anyone search without a warrant.
In most if not all states you need a warrant to have your residence searched. This can be due to either a CI (confidential Informant) or just being in the right place at the right time. Ex... being you get the cops called on your ass for a domestic dispute, now they have reason and probable cause to come in and search. Same with a CI if they have prove you are selling or dealing they can come in and search. Never be intimidatted though guys, without a warrant they cant due shit unless they are there for something else that would allow them on the property such as a domestic situation ext. without that they cant due shit unless your ass in on parrole then they can do whatever they want sorry:(
Never admit what you do to anyone.
I don't care who it is your dad, mom, brother, ext... someone always has a big fucking mouth. If something bothers them they will talk about it. Just keep this shit to yourself and maybe, maybe your wife if you have been with her for years.
Never pay for anything in credit cards!
If I really need to explain this one you should not be ordering gear to being with, but obviously they can track what you bought due to your financial records.
Use a secure email
For fuck sake guys come on, this is one thing you all should know. anything that is free is not secure, gmail, hotmail, yahoo ext can get you fucked. Use a secure email that is encrypted and hosted in a country that will not co-operate with America. I'm not giving away the answers but come on due some research its easy as fuck and if you are willing to pay for gear why not a secure encrypted email hosted in a different country.
Confirm packaging method with source
Even if your pack is searched and sent on they will have to see what is inside. Confirm how they are sending and what carreir they use. Maybe mark the outside somehow so only you and you alone can recognize if the source sent it. Example, tape! They have to open it guys even if they send it through for a controlled delivery with some electronic device inside. Confirm a colored tape they will use or a marking on the box that only you will recognize to indicate that they sent it.

If i think of more i will post, i just wanted to get this out there for safety reasons.