Enthusiasm is always a good one! It helps if you have skills in maths and understanding how the world works. Good communication and teamwork are also very handy (although there are lots of engineers without these skills too). I think spatial awareness and being able to visualise ideas are useful characteristics as these help you to be creative and come up with solutions quickly and on the spot.
Agree with enthusiams. From that, add diligence (where you’re willing to keep working on a problem until it’s fixed, not giving up). Also flexibility, my boss might come in tomorrow and tell me I’m being switched to a completely different project, I need to be ok with that be ready to dive into something new if needed without complaining.