This kind of shot isn't as difficult as one may expect. It is different from a greenside bunker as in most shots the ball will be hit first instead of the sand. However it is important that you have a good command of your overall swing particularly your impact position.
The first thing that you need to assess in the bunker is how good is the lie and how high is the lip of the bunker. If you're hitting an approach shot and the lie is quite good and the lip is low enough to hit your desired shot, you can address it like any other shot from the fairway. The only difference will be that you need to hover the club above the sand at the address position. Your main focus then is to make sure you hit the ball first followed by the sand. You need to feel that you're compressing into the golf ball by hitting down into the golf ball with your hands in front of the clubface.
The distance should be around the same as if you hit a normal shot. Now if you're confronted with a difficult lie when the ball is sitting down a little or when the the lip is too high, you may have to confront this shot like you would a greenside bunker. This is where you may need to take a PW or SW and take the sand first so you can easily exit the bunker. This is always the safest shot as there is always a risk when hitting the ball first that you may catch it 'thin' and cause the ball to collide into the lip.
Lastly always remember when deciding on a certain shot that you choose the shot that is the safest to execute with little chance of incurring a high score on the scorecard.
If you need any further help when playing within a fairway bunker, just book in for a session.