What signs do you typically look for to spot and nurture potential future IT leadership? Looking for specific approaches to identify future leaders early.

I look for soft skills first. Does this person get along well with his peers and customers. Do they know how to communicate well without getting flustered or frustrated under stress. Would I put them in a room with my boss or my peers and expect them to have a professional, direct, and data driven discussion. Are they comfortable with saying that they don't know the answer to something but are able to find it? Have I been able to give them small projects or initiatives without every detail needed but still be able to determine how to fill in the gaps and successfully deliver. Those are just a few things that I look and have worked really well for me in the past when promoting from within my team. 

A few different things to look out for and consider as indicative:
1. Attitude/behaviour - positive, engaging, professional, genuine/authentic, deliver.
2. Little guidance required, autonomy/agency.
3. Wanting to learn, try new things, be challenged.
4. Resilient, a bit of 'bravery', adaptive, assertive.