The Basics
The following is a list of general tips and tricks for all heists.
Don't speed through the safehouse when starting the game for the first time. Take a moment to practice the basic mechanics of the game. You practice opening doors, cracking safes, and firing your weapons without any repercussions. Don't squander the game's one calm moment.
When starting a heist - especially if it's a new scenario to you - take time to case the scene. The last thing you should ever do is rush into action. Even the game's simpler jobs, like Jewelry Store and Bank Heist, can go horribly wrong if not planned out. Learn where the money, guards, and cameras are located before putting on your mask and alerting pedestrians.
Remember that doors can be opened several ways. You can always pick the lock, but saws, drills, and C4 charges can do the job too, with saws and C4 working the fastest. For doors requiring key cards, the ECM jammer will also do the trick.
After subduing civilians, do not forget to zip-tie their hands. Doing so turns tied civilians into hostages. The more you have, the more cautious law enforcement will be about attacking you.
When drilling into a safe, never abandon the drill to take care of other business; make sure to stay relatively close. Drills often malfunction, and will need to be restarted to finish their job. Staying near the drill also prevents police from gaining control and shutting it down.
Bottlenecking is great strategy for any shootout, and you'll find yourself in quite a few of those. Bottlenecking is when you entrench yourself in a room with, preferably, only one entrance, forcing the police to come at you from one direction. This allows your team to camp in one spot and fire at cops in practically a single-file line. This is also a great time to throw down a doctor bag and ammo bag, fortifying your position with supplies
Learn to daisy chain bags rather than carry them. It's much faster to grab and throw a bag along a train of teammates than if everyone were to run back and forth for multiple bags. This is unless the number of bags is equal to the number of players - in that case, one bag per person works just fine.
Most jobs give you the chance to escape with extra loot. If you're doing well and feel confident in doing so, make a break for and extra bag or two. Be on the lookout for loose money or jewels as well. When waiting for the escape van or holding out against cops, you can pick up these loose items for bonus cash.
Finally - and this really should go without saying - don't be afraid to take your game online! Playing alone limits you to a team of three, and your teammates' AI cannot match the prowess of actual players. Even if you're new to the game, you can always follow and support Payday 2 veterans during tougher jobs.
