AIDA

AIDA http://www.youtube.com/watch?v=y-AXTx4PcKI
A attention
I interest
D decision
A action

Attention - keep your Senses open and feel all changes. You'll see the opportunities.
Interest - some of them do interest you.
Decision - decide which are good for you.
Action - do action to get them done.

Some ideas from here are used in GTD (GetThingsDone) - GTD suggest a method to allow you to be free and to be able to have more attention.