Liz,
Do a search for "subscription management" there will be a ton of discussions. I've posted quite a bit about this. Questions you need to ask:
- Are you using Workspaces?
- Do you need different languages?
- is this a global page or do you need one by country?
- which communication types will you post on each page (ideally same set for everyone)
- do you know which opt in/out rules exist for the countries you operate in? (best to use the CASL rules globally though --- opt in).
Usually you can setup multiple unsub page+form, one for each country/language and then update Email Templates to link to the correct ones with the correct footer text. You can also do the footers in Snippets/Segmentations if you want to be really slick.
If you have Workspaces, then you will post one page per WS along the same lines.
You may also need to worry about prefill and cookied emails. There are ways around that of course.
http://www.marketingrockstarguides.com/subscription-management-tips-for-marketo-454/