I'm prettymuch like prettyshady....

The main thing is frame protection. There are two things that will damage your frame: movement in the box and movement of the box.

Movement in the box-secure the frame inside the box with "dunnage," which is no more than packing materials. use something that won't rub the frame and damage the paint, and has enough density/material characteristics to dampen internal impacts. A box cut to fit goes a long way, and then strategic dunnage that limits movement in the box will complete this part. Secure everything else if you can, or protect it and the frame from each other.

Movement of the box-due to exterior forces (UPS/USPS/FedEx, etc). If the box is dropped, squeezed, etc, the frame can be damaged by external forces. Be sure to put something in the fork ends and the rear dropouts, and brace around the RD hangar to remove the possibility of it getting bent. I have made the mistake of not doing it, and was forgiven. My UPS friends tell me that the box should withstand a 10-foot drop.

Secondary is box size.
Choice A is a frame box, then use dunnage and frame-protecting pieces, secured inside so as not to damage themselves or other bits.

Choice B is a bike box cut down to a size where the frame fits and packing fits and little else, securely re-taped or even banded to keep the box's integrity. I open up the box like a pizza box, and keep the stapled corner edge intact, then cut as square as possible, as small as possible. With tons of packing, you can use a whole bike box, but will pay through the nose.

A few things I've learned:
Cardboard will scratch a frame and rub off paint.
If it can move, and damage anything inside a box, it will, whatever it is.
An unsecured, well-padded frame can still come right through the end of a box.
Removing the fork is safer, better for the frame and the fork, and allows a smaller box.
108'' is the magic number, length + girth.
A roll of plastic wrap or that foam stuff can do wonders.
The smaller the box, the better the chance any damage is the goons' fault.

Bike shops are your friends.
I've never paid for a bike box or a frame box, but I've bought my share of bar wrap, cables, and a tube now and then.

I ship frames coast-coast. In fact, NC to CA is between $23-$26 with delivery confirmation. I use Parcel Post. If the person getting the frame wants it Right Now, I'll be glad to ship it any way he/she wants to pay.