I was really paranoid about today because even after reading a lot of the posts on here, I was still missing a bunch of questions in my forms. We went to Frankfurt this morning and waited (even though we had an appointment and were early) for about 2 hours. But once our number was called everything went pretty fast.
You go to the window and tell the person what you are trying to file. They check your forms and tell you how to answer the questions you couldn't fill out yourself (We filed I-130 and G235a and I had a lot of unanswered questions in them because I didn't wanna mess up the entire form because I wasn't sure what to write). They just ask you to fill those gaps real quick and then you give them the copies of your marriage license and the US-citizen's birth certificate and a picture of each of you.
They send you to a different window to pay the $355. You bring back the receipt and they review everything.
Then they ask you to wait for your number to be called again and once it is they ask for the first part of DS-230 (I also had questions about that form and they willingly helped again) and a copy of your passport.
They will immediately give you the checklist (the one you fax back once you gathered all the documents) and instructions for the interview.
Well, that was what we did today and I thought it would be a lot more trouble. This post is just meant to calm people (who are like me) down
On a brighter note, I wish you the best with your journey! 