I personally feel powerless, or that it requires a huge amount of work to have a significant impact.

If what you say is true, It could be very persuasive to inform about the expected impact a single person could have by just doing X.

For example, describing how contacting MPs work, why would they care about what I say? giving a specific example, with rough estimates of number of people that need to contact or if it's more important the words chosen to achieve impact

I would be interested in reading a good blog post describing the expected impact of activism in politics, especially on topics that I really care about, like privacy and freedom.

I want to know what powers I have to change the things I care!