You can often predict when a driver is likely to move into a different lane on a multi-lane road by watching traffic ahead of and around him. If he is overtaking a slower car or cars up ahead in his lane are slowing, you can expect him to jump lanes. Cars also tend to change lanes when following a large vehicle they can't see past.
Distracted drivers sometimes move over unintentionally and won't always correct because they don't recognize that someone is beside them. So drivers talking on cell phones, applying make-up, or holding a large cup in their steering hands should be given a wide berth. Even undistracted drivers don't always take a real look before they move.
But the strategy for passing all these sorts of drivers is the same. Minimize your time next to them, and stay wide as you do. This applies to two-lane roads as well as those with more than one lane going your way. There may seem to be no reason for a driver you are passing on a two-lane road to cross the centerline, but be ready anyway-they might just be unaware you are there and drift across. In particular, be wary if a vehicle you are overtaking begins to slow as you pull out. He could be making your pass easier or he could be preparing to turn into a drive you haven't seen on the left. I have heard of several riders who were taken down by this scenario.
The driveway or road on the left could also hold a vehicle that is planning to turn out onto the road opposite your direction of travel. It is something to consider and look for before you commit to passing.
Still, the likeliest source of danger is the car you are passing, so the best set-up for passing on a two-lane road is try to ride in a position where the driver can see you in the mirror while you wait for a safe opportunity to pass. Signal before you start to accelerate, pull into the left side of the left lane as you pass, keep an eye on the car you are passing as well as potential sources of conflicts (he is more likely to run you off the road than to collide with a vehicle that pulls out from the right, for example), and continue to accelerate after you are ahead of him to open up a gap. This is definitely the time to use all that power you paid for. Downshift a gear or three before you start to pass and rev it to the max before each shift. The reasons you want to open up a gap between the car and yourself are 1) slowing down right in front of him is likely to annoy the driver, 2) opening a gap gives you a cushion if you have to brake for an obstacle up the road, and 3) it "sells" the pass-the driver isn't likely to think about re-passing you. If other riders are behind you, the gap you create should be even larger so they have enough room to pull back into the lane and still leave a gap.
On busy four-lane roads, you want to make a quick pass because there are likely to be faster vehicles overtaking you in that left lane. Going past a long truck at 0.5 mph faster than its speed while traffic backs up behind you and then taking your time to get back in the right lane is asking for trouble and creates potential conflicts. You may have to go faster than you like for a quarter-mile or so, but do it anyway.
What about overtaking a slower vehicle that won't get out of the left lane on a four-lane road? The potential for a driver to move over into you as you pass him is greater than when you pass on the left, and if you come up behind them and give up on him changing back to the right, wait a second or two after you move to the right before you accelerate to pass to be sure he hasn't recognized that you want to pass and decided to move over. Other than that, the standard rules apply: be conspicuous, avoid blind spots, accelerate hard, and ride wide to give you a cushion as you pass.