A good lookout is imperrative! No matter where you are - low level (<2000`)midweek especially (watch out for the fast movers), but a good listen out and lookout in any airspace is always important. I am not saying sacrifice good flying skills at important stages of flight but like Spacers example, you never know when other aircraft flown by dullards will pitch up right in your HUD. Especially the civvies that think its alright to disregard that MATZ! . .After you have been scared a few times I bet your lookout will be improved exponentially.
Lose sight, lose fight!