I think where 'creativity' and art can come in is in the management of conflict situations...and general 'people skills'. There is definitely no clear-cut answer to handling many of the various such incidents which occur in any game... if it works, it's probably right .....although later reflection may suggest to you how you might have handled it even better! If your approach to a specific incident doesn't appear to be working, first you need the sensitivity to realise this, and then you need to consider doing something different. Experience, coaching and watching other umpires provides you with a 'toolkit' of different things to say and do, plus, hopefully, the sense to know which ishould be 'first choice'. Sometimes, for example, it's just finding that brief comment which (usually) defuses a potentially explosive situation. The only 'science' is a bit of understanding of 'behavioural psychology' Mostly it's experience, and a desire to improve this area of your 'job'.