What are some good safety tips for a 3D printing beginner?
Technically, you should never leave your printer running unattended. Printer fires are rare, but it can happen, especially with cheap printers with poor quality control. Personally, I would just make sure that there is a fire alarm near by, so you'd be alerted if there was a fire.
Also, the fumes concern is valid in the sense that you don't want to sleep in the same room as your 3D printer. The following article points out that if you are spending time in the same room without proper ventilation you'd benefit from potentially using an enclosure with a HEPA filter. Also, the article points out that using PLA may be a safer choice than other materials such as ABS or Polycarbonate when it comes to harmful particles: https://3dinsider.com/3d-printer-fumes/