I just donate by whatever means the project offers. Sometimes it's paypal, sometimes patreon, sometimes GitHub sponsorship, sometimes something else like OpenCollective. Read the readme or homepage of the project to see what options they take.

I never contribute monetarily but I do contribute bug fixes, documentation fixes, spelling and grammar errors, even in languages I don't know.

is there anything you would recommend?

You'd need to donate via whatever means they accept donations, it's not something you get to choose yourself. Unless you meant that you are going to keep contacting FOSS projects to ask them to set up new donation methods?

Personally I donate via crypto or other means that they allow donations via credit card (Liberapay / Ko-Fi work well IMO) . No Paypal/Venmo since I can't use those services - some FOSS projects I don't donate at all if they only accept Paypal.

Well, I often just do a bank transfer or card payment. I've tried to use Monero, but I've had trouble getting ahold of any crypto without selling my soul to Guardarian.