My policy is to start narrow and gradually increase (using friendlies and "dead wood" matches, obviously) until I find a good "natural" setting for my tactic and players. From there, I narrow it for my defensive tactics and widen it for my attacking variants. Seems to work!
Ideally, you want to play as wide as the opposition will allow you too if going for goals, simply because it gives you more space to work in. That's what I've found, anyway.
And please, lay off the text speak. Not only do we have "foreign devils" round these parts who may not understand you, it's incredibly annoying and, most importantly of all, it makes you sound like an inbred.