Your point is very good! It needs to be specified how our signatures will help in the fight against mass surveillance. We signed, and now what? Spread the word. But what is next?
I think the solution to this has to be on multiple fronts. It would be a good idea to push for laws which forbid certain kinds of surveillance. In the US the situation with the constitutionality of the NSA activity needs to be clarified. In the UK it would appear that the activities of GCHQ - particularly using DDoS and other "dirty" methods - is against the existing computer misuse laws. Investigating and following up on that would be useful. Probably they will make all of that retroactively legal, but there might be an opportunity to challenge and stop that in parliament.
On the technical front if you're a software engineer you can spend some of your time helping to develop, test and debug the various encrypted communication systems. Often security audits are needed. If you're not a software engineer then find out how to use encryption tools - PGP, XMPP/OTR, Tor, Bitmessage, etc and encourage your friends to use them.
