Just been through this twice and thought I would share! DS needed passport pictures for his UK and US passports and I've just had them done while he was 6-7 weeks old.
His UK passport photo was taken with him lying on the floor on a white mat. Unfortunately his head kept turning to the side, but I was able to get him looking straight on using a muslin bunched up under his neck. He's basically mid-scream in the photo, but the guy said they aren't too fussy with baby pictures here.
US has different requirements and are a lot stricter; according to the photographer they want the baby's eyes open and mouth closed. Given our first experience, I wasn't sure how I'd be able to do this---then had a flash of inspiration. Every time I've given DS Infacol, he opens his eyes wide in surprise and purses his lips! So I just gave him a little bit, got my hands out of the way quickly, and the guy snapped the photo on the first try! It looks perfect!
Oh I sooooooo agree about the sling. As it was, I was at the U.S. Embassy for over 3 hours (though it says 1 hour on the website). My 'appointment' meant nothing at all. There are stairs everywhere, and even a few down into the toilets with no ramp. I ended up helping another mum carry her pram (while carrying the baby in the sling and a heavy backpack). It's a horrible place, I hope I never have to go again!
Bloody nightmare going to the US Embassy. DH and I went with DD (then aged about 1 1/2) a few years ago to sort out his ITIN number. The security staff confiscated DD's toy phone as it was 'a phone'. No matter how many times we pointed out it was a toy from ELC and only capable of phoning a Lion and a Panda they wouldn't see sense. Numpties.
Actually, you have to laugh at the american security sometimes. A few years ago I went to NY and went across to see the Statue of Liberty where the security was quite strict. I set off the metal detectors and explained that I had metal pins in my spine following spinal surgery. The female security guards reply was 'can you remove them please' err no, it took a team of 4 surgeons about 8 hours to put them in