If they face off at each other and sort of "twitch" or lip lock, gengerally thats a sign that they are pairing. When you notice 2 bullying the rest and chasing them all around and cleaning flat surfaces (leaves, glass, intake tubes, etc) then you have a breeding pair on your hands. You'll notice a small white tube drop from the male and a thicker yellowish tube from the female. She will start to get pretty plump (looks like she is just really full on food). If you have other fish in the tank besides the angels, I would put your pair in another tank when you see this. Otherwise, I'd leave them alone and find out what kind of parents you have. Some will eat the eggs after laying them, some will defend them aggresively and even raise the fry themselves. I've had quite a mix over the years. Some good parents, some bad. I sold a breeding pair to a LFS last fall that was one of the best parents I've ever seen. They actually reaised about 200 fry in a tank with other angels. They were super protective, and short of the brave fry that ventured away from them, I had very few losses. I wasnt interested in raising that batch, so I left them in expecting them to get eaten. The parents were just too good at their jobs and I was stuck with 200 baby angels to sell.
I ordered some manzanita 2 weeks ago that is supposedly sitting on my doorstep as we speak (I'm at work). It was shipped USPS, so I'm worried I'll come home to a box of sawdust. USPS really does suck. But... knock on wood... I've yet to have any issues with livestock shipped USPS. However, I will say that most of the folks I've bought from on here have been amazing about their packaging.