>How did you started on your journey with robotics?

Building RC cars, RC quads, 3D FDM printers, and LinuxCNC/EMC 3-axis mill retrofits.

>what's handy to learn in the first place?

Depends on your learning goals, and desired platform budget.

1. Some sort of basic EE topics in a school, or Ham technician license

2. Basic project book on Arduino: blink LED, move RC servo, spin motor, and make speaker beeps etc.

3. Build cheap Arduino turtle bot kit, racing drone, and or a RC car kit

4. Build a 3D printer kit like LDOmotors voron, or join a local space to get CAD/printing skills

5. ROS tutorial to connect Arduino turtle bot kit to simulated environment

6. Courses on Forward Kinematics, Inverse Kinematics, OpenCV Machine Vision, POMDP, NN, Kalman filter, and PID motor control.

7. Build a small 7-axis robot arm path planner in ROS simulator

8. Build a Autonomous mobile Robot with your SLAM of choice, and bolt arm to turtle/tracked platform

9. Gain the wisdom of the tribe around guidance and navigation problems

10. Build some sort of walker: Heaxapod (easy), quad (challenging), and biped (hard)

11. Remember to test everything outside in sun, wind, and rain. There is a lot of expensive garbage products that only sort-of work in ideal circumstances.

Again, the path may be greatly simplified if your goal is only to use robotic platforms... rather than build something expensive. For example, the Yarbo core platform looks like a fun mid-sized project to retrofit, and defunct units are under $1.5k off auction sites.

Have fun =3