The ACLU also does a lot of great privacy work, so donating to them is also a good idea if you care about this stuff. National ACLU does a lot of great work, but I personally suggest giving to your local affiliate https://www.aclu.org/about/affiliates, as they are often the ones who work on local issues that are likely to directly impact you. We do privacy lobbying at the municipal and state level and our local ACLU affiliate has been a huge, huge ally.
There are also other great privacy orgs that are not quite as big but are also fantastic in their own ways, like Restore the Fourth (which also has local chapters like shameless plug) rt4mn) Fight for the Future, Demand Progress, Cato, and Privacy International
Also, If you want to do more then just donate, you can help the EFF with its lobbying efforts by joining the Electronic Frontier Alliance https://www.eff.org/fight We participate, its pretty great.
> We do privacy lobbying at the municipal and state level and our local ACLU affiliate has been a huge, huge ally.
I disagree with them on a whole range of issues, but when it comes to privacy and mass surveillance they are almost always spot on. Most of my disagreements in that area have to do more with political tactics and messaging then anything else.