I use Suppressor Services – Silencer Shop for all my stamps, then what I would recommend is once your paperwork is filed and ready use SilencerCo.com and find a kiosk and get your picture and fingerprints done there so you can keep them on file forever when you want to buy an NFA item, as you start your NFA journey. You will also want to go the eForms (atf.gov) and sign up for an account. Make sure you keep very accurate records as you will need to know where there are and what your passwords are. I would also recommend a records book to keep track of all of your NFA items such as serial numbers, make and model in your records. Most likely you’ll only need them as you buy new devices but is you were to lose something, or it got stolen you will want a good record of the item(s) to give to the police and ATF agents. If you don’t have a safe, I would also recommend one and get a smaller one for your paperwork for inside of it and make sure they both have fire ratings on them, protect your records.