Hello all. I'm new here and I've been looking through the forums for many days. However I have two questions that still aren't clear to me from all the commentary. Anyone willing to help me out?
1) Is it essential that the initial I-129F pack be sent through USPS or Fedex? I was wondering if it's ok to send by regular mail. Currently running on a tight budget and know this entire process is going to be quite expensive!
2) Some of my supporting evidence of an ongoing relationship (e.g. cards, emails, chats) and evidence that we met in the past two years (e.g. hotel receipts, even receipts) are in Spanish. Do I have to translate all of them? And is it ok if I translate them myself? I'm bilingual in Spanish and English. I understand that when it comes to birth certificates etc it would be good to get someone else to translate but since these items aren't as "official" I'm not sure if I need an official translator. OR if they even need to be translated since again, they aren't government issued documents.
Thanks to anyone who can help! I'm SO nervous!!! 
First of all.. Hi! and Good luck to your journey.. This is what i did.
1. You can send it by regular mail as long as it goes through. But the thing is, if you want to be sure that it goes through, you can use USPS with tracking number service. I used the flat rate envelope and i think it was $5.99 only. Aside from using the flat rate, it doesn't matter how much it weighs. I think fedex is more expensive.
2. I didn't need to translate in english all the proofs that i have, though receipts were in english, but the card, emails, send it as it is. maybe for the following chat/email, use some english words such as "i love you" coz you need more proofs during interview itself. I believe you only need to translate for special documents such as birth certificate and letter of employment, bank statements or something like that.
3. You'll be fine.. Just make sure you followed the checklist that this website has. Don't forget to make copies of whatever you're sending them.
I'm just sharing what i did when i sent mine.