The driver of a vehicle about to pass another on a
lane highway waits for just the right moment,
accelerates, moves around the vehicle ahead, then goes
back into the right lane again. A simple maneuver?
Not necessarily! Passing another vehicle on a two
highway is a potentially dangerous move, since the
passing vehicle occupies the same lane as oncoming
traffic for several seconds. A miscalculation, an error in
judgment, or a brief surrender to frustration or anger can
suddenly put the passing driver face to face with the
worst of all traffic accidents 
 the head
on collision.
So here are some tips for passing:
D “Drive ahead.” Look down the road, to the sides and
to crossroads for situations that might affect your
passing patterns. If you have any doubt whatsoever
about making a successful pass, wait for a better time.
D Watch for traffic signs, pavement markings and lines.
If you can see a sign up ahead that might indicate a
turn or an intersection, delay your pass. A broken
center line usually indicates it’s all right to pass
(providing the road ahead is clear). Never cross a solid
line on your side of the lane or a double solid line,
even if the road seems empty of approaching traffic.
D Do not get too close to the vehicle you want to pass
while you’re awaiting an opportunity. For one thing,
following too closely reduces your area of vision,
especially if you’re following a larger vehicle. 
Also, you won’t have adequate space if the vehicle
ahead suddenly slows or stops. Keep back a
reasonable distance.
D When it looks like a chance to pass is coming up,
start to accelerate but stay in the right lane and don’t
get too close. Time your move so you will be
increasing speed as the time comes to move into the
other lane. If the way is clear to pass, you will have a
“running start” that more than makes up for the
distance you would lose by dropping back. And if
something happens to cause you to cancel your pass,
you need only slow down and drop back again and
wait for another opportunity.
D If other cars are lined up to pass a slow vehicle, wait
your turn. But take care that someone isn’t trying to
pass you as you pull out to pass the slow vehicle.
Remember to glance over your shoulder and check
the blind spot.