I saw a bit of bad advice earlier in the thread...
FedEx requires you to set up an account to ship, and you need to give them a credit card now. There is no way to conceal who you are with Fed Ex shipping other than some other pretty major crimes. I do agree that Fed Ex is reliable and the least likely (next to USPS) to get intercepted. But they don't need a warrant to check packages.
Private couriers work great for getting stuff across town. Of course, you have to open an account with most of them and this generally requires some type of identification and a major credit card. When I worked for a courier service we did indeed have a client who used it to send considerable amounts of pot around. However, he was eventually busted for it. Tons of private couriers smoke pot too, and LEO pulled over that driver and smelled what the driver had been smoking and wanted to search. They brought a dog. Courier didn't get arrested, but they nailed the client hard.
As far as oder, you have two problems. When you handle anything that the dogs will hit on the scent gets on your hands and you transfer it to anything you touch. What you want to do is get some latex gloves, a couple newspapers, a couple zip locks, and some glycerin. Put what your shipping in the zip lock, seal it with a layer of glycerin, wash hands, change gloves, set up another newspaper in a different spot. Move the package into another zip lock using the newspaper to handle it. Seal that with glycerin. Repeat again. The best method I've come up with is to send a pair of shoes. Shoes have wadded up paper inside of them when they are new, so you simply put your product ahead of that, and pack the paper in. If they did example it and X-ray it would look pretty normal. You can get prepaid boxes for a given weight from the post office. They sell them under priority mail. Cost a bit more, but ...that isn't the issue. If you know your weight, you'll be fine.
The odds of an intercept are pretty low.
As far as internationale goes. Letters don't have to be approved by US customs coming into the US (yet!). All packages have to clear customs. Customs handles hundreds of thousands of packages a day, and a trillion dollars worth of goods coming in and out in airports, boats..etc They do use dogs to sweep for things occasionally, but it's a hit and miss thing. They don't have enough manpower to get everything. Make it look normal, take precautions against scent, use quality shipping materials and don't get excessive with the tape. I've gotten stuff in the mail from several countries in Europe, shipped in film cannisters, VCR tapes, and even in a plain ol' mason jar. There isn't much sneaky you can do that customs hasn't already seen. People have tried literally everything from hollowed out boards in packing crates, to actually compressing drugs into the shape of the item to be used. (Candles get stopped every time for this reason). As far as what they do when you send something out of the US to another country ...that's anyones guess. Customs does a pretty good job, so it's risky. They are looking for a lot more things than drugs.
Oh, one thing.. If you are shipping internationally make sure you have a valid address that matches the name on the package. They do check that. And don't do anything stupid like stick an address from a country other than where it's actually mailed from on it.