I happen to have done my last month and I sent mine in by internet which save me $10. Okay what I want to add is....Don't send them a colour picture of yourself. If you are capable with using Photoshop, take the photo and convert it to black and white and adjust the grey ranges and shades to your face. I made a pig mistake by giving them my picture it colour which they willing to take. Problem is...they did a conversion to a black and white photo and aiyo....I end up with dark complexion and everything is just wrong! The only way for me to solve it would be to go pay for another passport.
So get your measurement right, follow their tips on how to frame your shot..but after all that is done...do the conversion yourself and try to adjust the tone to your face in black and white. At least if you submit it, they will use it as is or at least it should come out better then what they did with mine man when they "help" me convert it to black and white.