Which way is up?

[LesB]

Just transitioning from the concept stage to the building phase of my project, and I have a very basic question.
So I need to solder the header pins on to the Moteino for connecting the FTDI adapter.  Which side of the board to install the header? 
Does it matter at all?   
I'm thinking I want to be consistent in this regard with all the headers and I don't know if the other headers are best installed on one side or the other for interfacing with compatible devices.

[Felix]

Hi and welcome,
There is no "correct" way per se. It's whatever works better for you. I tend to solder them horizontal with the board and on top of the PCB (plastic holder of the header on the same side as the components).
Here's a photo showing such an example and how it would mate with an FTDI serial adapter:
Moteino R4-USB by Felix Rusu, LowPowerLab.com, on Flickr

[ColinR]

This is my preferred orientation. Makes the LED easier to see. As I have commented elsewhere, however, it makes it impossible to see whether I have an RFM69W or RFM69HW after I install it.

C

[LesB]

Ah, the LED.  That's a good reason to mount the header as such.
Thanks,
LesB