General tips:

The only way to lose is to run out of stealth tokens, so they are extremely important. You want in most turns to take the minimum number of risks to keep those stealth.

Triggering an alarm is generally good, because you can control where the guard is going.

When there are multiple players on one floor, you want to be extra safe in a tile where the guard will rarely move so as to not take the risk to lose 2 or 3 stealth until your next turn.

Spreading players on different floors is extremely good since that makes the guard move less between each of your turns.

By putting your mouse in the patrol deck (top right), you can see which tiles the guard has already visited if you need somewhere to "hide".

Peek or move:

Usually, there are two situations for you:

Either you are safe, you have no risk to lose a stealth this turn, and few or no risk to lose a stealth next turn. On that case, you usually want to peek at tiles, add hacks in computer, add dices and roll on safe. You could decide to move to unknown tiles during your first two actions.

Or either you aren't safe, again two situations: either you have an high chance to lose a stealth, on that case your main goal is usually to find a way to be safe, that can be by drawing an event, moving to unknown tiles even in your third or forth action if you aren't safe, triggering an alarm and going back to where you are, limiting the risk by ending your turn in a safe or mostly safe tile... Or either you have a moderate chance to lose a stealth, and want to limit your risk while still doing something useful.

The floor 1 is pretty free (at least in 1 or 2 players) since the guard only moves 2 per turn. So taking even a small risk in that floor can be not optimal. It's so free that moving up to floor 2 peek two tiles and going back to floor 1 can often be a good idea.

On the opposite, floor 3 can become a problem really fast. So taking a risk to move to unknown tiles can be a much better idea.

If there is any big problem on any floor (e.g., deadbolt in the center, fingerprint in entrance of floor), put full priority on trying to resolve it.

If you have more stealth than your teammates you should take more risks. If you have less stealth, you should take fewer risks.

Triggering alarms:

Triggering alarms can often be good.

You can trigger an alarm to not make the guard be one away from his destination which will make

If the guard is one away from his destination, and you can trigger an alarm three away from him, that will make the increase of movement patrol card be delayed by one move.

You can create multiple alarms to be able to decide all or most of it's path during a turn.

Cracking the safe:

You usually want to add dice 3 times to a safe. With normal Peterman and/or Stethoscope, you want to add only 2.

If you add one more, it's to have more control to when you want to crack the safe (or minimise extreme cases). Adding 5 or 6 is useless outside of wasting moves/preparing for later.

If there isn't all the tiles in the row and column revealed, rolling has very few utility.

When you crack a safe, you increase the movement of all guards on the current and below floors. So you want if possible to crack safes in order.