Honestly, I donate enough money to politicians to make them stand up and take notice when I email or call them and share my thoughts, which leads me to the conclusion that people in the middle and lower class are going to need to find ways to pool money in such a way that they can change their party politics. It's not that all politicians are completely motivated by money, but IMO you unfortunately have to aim at the lowest common denominator.
You can only donate $3500 to any politician. (legally, if you do something illegal and are not caught...). There are complex limits notice when you say something. (for a small city that limit will make them listen, but nothing national or even a large city)
What you can do is get out votes. People knocking on doors is still one of the largest drivers of votes so if you organize those systems they will listen to you.
I donate to the party, and I donate at the individual limit. At that level they still care because people who donate at that level are connected with other people who donate at that level, and those people tend to reach out and coordinate. Periodically I get emails from other donors who ask me to reach out to such and such a person, a candidate or a party rep, and encourage that they take a look at X issue through a particular perspective.
I think more people would benefit from forming Super PACs and using that as leverage in pushing political change with parties.
I am not at all familiar with the US system. How come there is a $3500 donation limit to politicians, but the tech billionaires have donated hundreds of millions to the inauguration fund?