I think it's important to do something practical. Even if you're a full time warrior for justice, screaming all the time will burn you out. You have to do practical stuff. Volunteer to clean up, volunteer to be a mentor to at-risk youth, volunteer to help people look for jobs, volunteer to help build houses, volunteer to teach people English, volunteer to help people sign up for social services, volunteer to make food and distribute food, etc, etc, etc. Pick something practical and do it.
...and it'll also help you advocate for systemic change in multiple ways. It gives you far better insight into the true nature of social problems, so you can advocate more effectively about them. It also signals to people that you actually care about the issue and aren't just yelling about it because someone on the Internet stirred you up. It gives you legitimacy and authority on the topic.
Doing ONLY practical stuff can also leave you drained as you feel overwhelmed by the scale of systemic issues. So having a balance of both sides, both practical change and pushing for systemic change can be very powerful.
And keep in mind that social media is largely an echo chamber. You're not really raising awareness by retweeting stuff on twitter to your like-minded followers. You need to get out there and talk to friends, family, neighbors, coworkers, and local leaders like at city hall, etc. If you've done a lot of practical stuff, you may be able to talk to local journalists and write op-eds with some level of authority on the topic.