I just finished the tutorial. What should I actually do next?

Most new pilots stall right here, so you are asking the right question.

1. Run the career agents. They are short mission chains that teach the main professions and pay out ships, modules, and ISK.
2. Pick one activity to try first: missions, mining, exploration, or small-gang PvP. You can change your mind later; nothing is locked in.
3. Join a corporation. EVE is much easier with people who can answer questions in real time. That is the whole point of a corp like GFVX.

Avoid spending all your ISK on one ship early. Fly cheap things while you learn.