Long story short: tell your Congressfolk to expand Medicare and pass the Baby Food Safety Act, the Global HER Act, the For the People Act, the John Lewis Voting Rights Advancement Act, and the Medicare for All 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, or use the email/petition tools in the following paragraphs.
Both Social Security Works and Public Citizen help you tell your Congressfolk to lower the Medicare age to 60 and expand it to cover vision, hearing, and dental care. Should you sign this if you support expanding Medicare to include everyone? Why, yes! It's a good idea, even if it isn't everything we want, and it could get us where we want a whole lot better than the Affordable Care Act did. And maybe your Congressfolk need to know that we support expanding Medicare before they'll ever have the guts to expand it to everyone. Also, too, as the petition says: "(s)eniors have eyes, ears, and teeth. It’s about time Medicare covered them."
The Environmental Working Group helps you tell your Congressfolk to pass H.R. 2229/S. 1019, the Baby Food Safety Act. You mean baby food's not safe? Well, Congress found dangerously high amounts of lead, mercury, and arsenic (among other toxic heavy metals!) in baby food, and the state of Alaska just found a high level of arsenic in Beech-Nut's rice cereal, which Beech-Nut has now recalled. So, yeah, we need to do better, but we don't even mandate that food manufacturing corporations test their products for heavy metals or warn good Americans if they find them in their food. This crap can damage children's brains, and we still believe children are our future, right? And if anyone pooh-poohs baby food safety by saying "hey, I endured worse as a kid," you need only respond "yes, I believe you did."
Daily Kos helps you tell Congress pass H.R. 556/S. 142, the Global Health, Empowerment, and Rights (or HER) Act. The Global HER Act would let foreign non-governmental organizations get American assistance even if they provide abortions (as long as they're legal in both America and the country in which they're operating); as it stands, our President gets to determine whether that happens, and, of course, when that President's a Democrat the "global gag rule" goes back into the closet, only to come out whenever a Republican gets elected. I, for one, don't particularly want to keep going back and forth about this. Our Founders didn't want the President to be that important, and any blow we can strike against a President's importance is a good blow to strike.
Daily Kos, the Sierra Club, and People for the American Way all help you tell your Senators to pass H.R. 1, the For the People Act. Meanwhile, Common Cause, People for the American Way, and the Daily Kos Liberation League all help you tell your Congressfolk to pass the John Lewis Voting Rights Advancement Act. And Public Citizen helps you tell them to do both. Dig Sen. Lindsey Graham (R-SC) trying to feed us fecal arguments about the For the People Act: "It does away with the states being able to redistrict when you have population shifts...you’d have some kind of commission redraw the new districts, and I don't like that. I want states where people are moving to have control over how to allocate new congressional seats." Actually, states would still be able to redraw districts: they'd just have to use commissions (not one "commission," Mr. Graham) to do it, which makes it less likely they'll redraw Rorschach-blot-shaped districts that only serve the interests of individual legislators. They know this bill's popular, and they know they can't win arguments against it, and that's why they lie. But we don't have to put up with that.
Finally, Demand Progress, MedicareforAllNow.org, Black Lives Matter, and Roots Action all help you tell your House Reps to pass H.R. 1976, the Medicare for All Act. Was I just advising you to tell your Congressfolk to lower the Medicare eligibility age to 60? Well, I was also saying you can tell them to lower it to zero, too; only a pedant would complain about getting both messages from their constituents, and although many Congressfolk are pedants (or, worse, pretending to be pedants), there's no reason we should tolerate such behavior. And given the kinds of "public options" passing at the state level, we might as well draw a clear line between what's "public" and what isn't. Having our government administer the health insurance is "public," anything else isn't. And if you worry about government doing it, ask yourself: are you happy with your private insurer doing it? Best to answer after you've actually tried to get health care!