I agree with /u/Searocksandtrees. There are no international, generic answers that fit all. A general idea of your location or the types of research that you are interested in will help.

That said, there are wonderful opportunities for volunteerism and donations. I helped run archaeological excavations for over two decades, and volunteers made everything happen. They were wonderful people.

I have a degree in Archaeology, and I agree with these answers, but I also have my own advice to offer. While Archaeology has a rather 'glamorous' reputation, partially due to the success of certain films, in reality it is hard, time-consuming physical labour. That isn't to say it isn't interesting- it is! that said, because of these factors, Archaeological digs are very frequently in need of volunteers.

If you have a University with an Archaeology department close to you, then perhaps send an email to somebody in the faculty, stating your interest and asking if they know of any companies that may require volunteers. Alternatively, you could try searching for Archaeological digs in your specific city. My advice to you: be prepared to work hard and get dirty. If you put enough into it, it will be a rewarding experience

Hi OP, while it's possible you could get an answer here - there are a few archaeologists here - it would be worth x-posting to their usual haunts: /r/AskAnthropology or /r/Archaeology