The Nightclub job takes place in - you guessed it - a night club, where you'll have to track down and steal money from the club manager's office. This can be a very easy job if you're paying attention.
Right off the bat, entering the club isn't an issue, even though Bain presents it as such. Keeping mask free, move toward the bouncer and stare him down for a moment to gain entrance. Now walk your way past the club goers to the rear corner of the building; head through the doorway marked "management."
Now this is where you need to start paying good attention. As you enter the storage area with the door to the management office, put on your mask. Now that you can actually take action, knock out any guards in this storage room before they are alerted.
At this point, you have a few options. You can blow the door with C4, alerting people. You can search for the keycard on a guard or around the club for quick access or use the ECM jammer for the same result. Your final two options, the drill or handsaw, involve the same strategy. As you drill or saw your way through the door, keep an eye out for any patrolling guards that walk through this room. Be quick, and you'll knock them out with alerting others.
Once the door is open, head up the stairs to the management office. Make short work of any final guards or club workers up here, and start on the safe. The method of getting into the safe isn't important, as you'll be grabbing the money and running as soon as it's open. Do so, make a sprint through the club before anyone can react, and you'll return to your van in no time with no complications.
Should you find yourself caught in a police assault, however, the management office makes for a good holding point. The small area above the stairs is a perfect spot for watching ascending cops, as well as any SWAT that drop through the sunroof. Use a Doctor Bag or Ammo Bag to fully entrench yourself.