Long story short: tell your Congressfolk to increase Social Security benefits, ban stock trading by members of Congress, pass a 15% corporate minimum tax, prevent big telecom corporations from price-gouging prisoners, and pass the Postal Service Reform Act. Use the tools in the upper right-hand corner of this page (or, if you're on a cellphone, the bottom of this page) to find your Congressfolk's phone numbers and/or use the email/petition tools in the following paragraphs.
Social Security Works helps you tell your Congressfolk to pass H.R. 5723, the Social Security 2100 Act. As Jon Schwarz explains here, the Social Security 2100 Act would expand benefits for all Social Security recipients, and it would also increase the minimum Social Security payment from 85% of the poverty line (which we all know is too low!) to 125% of the poverty line. It'd do other good works, too, but when Joe Manchin hears that it'll only expand benefits for five years, he'll bellyache about it. Let him! If the nation sees a pro-Social Security bill die at his gnarled hand, they'll want better Democrats in our Senate, and in the meantime House Democrats can run on their vote in favor of it. They still have to vote, of course -- apparently the bill's sponsor, Rep. John Larson (D-CT), hasn't put his own bill before the House Subcommittee he chairs! Here's how to get in touch with him.
The Project on Government Oversight helps you tell your Congressfolk to ban stock trading by members of Congress. Quite a few different bills (and promised bills) now address this matter, but we need to ensure they don't produce a bill riddled with loopholes you could drive a Mack truck through. We can't just say "don't trade stocks" and be done with it; we have to ensure their spouses also adhere to the ban (since hiding your assets in your spouse's portfolio is a common trick), and we also have to ensure they don't trade in things like derivatives and futures. A Congressperson may vote on bills that help corporations in which they're invested, and they may also investigate corporations in which they're invested; some will pretend offense that we think they can't separate their self-interest from America's interest, but, ah, we know better.
Americans for Tax Fairness helps you tell your Congressfolk to pass a 15% corporate minimum tax, so they don't get away with paying no taxes (or worse, getting money back from our government). Yeah, I'd prefer a 55% corporate tax on profits over $1 million (I'd keep it where it is for profits under $1 million), but a 15% minimum tax would do a lot of good, and I'd happily call it a stepping stone to where I'd want to be (which is, guess what, where we were in the 1950s). We can't keep going on having corporations pay nothing, and having governments pretend that "research and development tax breaks" are "incentives." The incentive to research and development is that expenses don't get taxed; everything else is horseshit.
Color of Change helps you tell your Congressfolk to support H.R. 2489, the Martha Wright Prison Phone Justice Act. As you know, prisoners pay an arm and a leg just to make a phone call to their loved ones, and when your Trumphole neighbor says well then they shouldn't have done the crime ha ha ha snort, remind them that prisoners who can easily stay in touch with their families won't go back to prison as much, so we all have an interest in making sure prisoners can do that without getting gouged. And, yeah, if you're feeling ornery, tell them that Captain Kirk wouldn't stand for a society that gouges its prisoners just because some corporation wants some unearned profits so their CEO can gild the plumbing in his 19th vacation home. Yeah, Captain Kirk don't play that! And Mr. Spock don't play that, either!
Finally, Public Citizen helps you tell your Senators to pass H.R. 3076/S. 1720, the Postal Service Reform Act, which would (among other good works) lift the onerous mandate requiring our Postal Service to prepay retiree benefits decades in advance. H.R. 3076 passed the House by an astounding 342-92 vote, while S. 1720 counts 14 Republicans among its 27 sponsors, but naturally Sen. Rick Scott (E-FL) blocked its quick consideration, claiming that the bill would hurt Medicare. By depriving it of the money our Postal Service doesn't have to begin with? I'd call that pretzel logic, but I know Rick Scott's not stupid, but evil, and he will say whatever lets him and his cronies privatize our Postal Service. People like him should never win so much as a Yahtzee game, so we've got work to do.