The serious answer is: very rarely they win important victories. It does happen though. Most of the time they spend their very limited resources fighting uphill battles against a government with nearly unlimited resources (and an ever expanding legal basis for their increasingly vast powers). While the EFF is trying to check the government over here, the government is over there expanding laws in their favor.

The government system of the US is now the size of Japan's entire economy fiscally. I don't see how that is ever going to be contained. There's no way to pass enough controls or restrictions to hold something that massive in place, and there's no way to afford to monitor all the restrictions even if you got them into place.

The other problem I rarely see addressed is culture. No two governments are the same. The US is an aggressive government, that is its culture (at least since WW2 or so), and that will be very, very difficult to change. Some people naively think you can trust a large government like the US Govt., as you might Sweden's government - but that ignores the fact that their cultures are drastically different.

Orgs like the ACLU and the EFF are very valuable institutions, and they're trying to do what few others are. The odds are severely stacked against them, but given the context is so extraordinarily important, it remains worth fighting for. Maybe all they can accomplish is to slow the process of rights erosion down, that too is valuable (some of course argue it'd be better to accelerate the implosion instead, rather than have a long slow erosion).