My wife has a green card and we did it ourselves. We applied, they obviously looked at the paperwork we sent in and the next step was a interview. We had to see a gov official to see if we were married "for real". We went it and after seeing our kids and listening to us he was close to approval. We (the wife and I) argued about some small detail and that sealed the deal- we were married "for real" in his eyes. Most people hire an attorney. I do not believe you can get a green card while living outside the states however- you have to live inside our borders to apply IIRC. Your living in Singapore will not help your case.