Re: What kind of notech skills.
TBH just be yourself.
If you have them (and there's is a very long 'official' list of desirable vs undesirable ones - eg through personal style creates atmosphere for open communication) then welcome aboard.
Im in the rh seat and its moderately rare to fly with the same person twice - all BA pilots lack the 'small base' luxury of building relationships.
As such my point is, put bluntly, I'd rather spend my 'one off' flight/tour with someone who naturally has good notechs rather than someone who acted in the sim and then defaulted to true 'less desirable' self. Trust me, there are a handful of faces who are already in and got in long before the importance of notechs was set down in company policy and truly became part of the corporate culture.
I understand this is curt and not helpful but I think if youre honest you'd probably agree. BA is huge, yet it's unusual to fly with someone unpleasant - there's a reason for this.
Just succinctly verbalise your thoughts, make time for the other person to advocate their position, do a 'mini review' here and there, when the other person makes an error point it out gently at first and in a way which keeps them on-side, use humour appropriately - there's nothing wrong with levity. How you do all these and other positive attributes, well that's notechs.