Turn the Opportunities system's assistance to minimal
Hitman 2016 has a new system dubbed Opportunities, where players can 'track' different means of assassinating targets via HUD overlay. It's a nice addition, but even if you're totally new to the game it's best turned off or to minimal. That way you'll still get the initial information you need to work out the rest of the hit without having the game put a big marker on screen telling you exactly how to do it.
Do a lap of the palace first before you attempt a hit
When you first arrive at the fashion show it's easy to be overwhelmed by the sheer size of the building, as well as the hundreds of guests, VIPs, and guards which patrol the place. Remember: you've been invited here, and as such you're free to walk around a large chunk of the downstairs area. Take a little walk around first: it's amazing how many people immediately try and sneak upstairs or into other restricted areas.
Listen to every conversation
Thanks to the Opportunities system, one of the best weapons in 47's arsenal is to listen in to what's going on around him. When circling the building you'll run into a whole host of conversations: some will give you overt clues as what to do next, while others may simply tip you off on a new escape route. Either way, it's all good intel, geared at telling the player - without showing them - what their next move could be.
Move quickly and decisively via crouch-running
One of the most basic things that gets Hitman players busted is indecision. The fashion show is rammed with people, most of whom can arrest or kill 47 should he be in the wrong place with the wrong disguise. The easiest way to avoid this is to open the map, find the route to where you're going, and work out the path of least resistance. Following that, crouch-running will see you move quickly and quietly. Use it to your advantage: even if a guard sees you, there's still a small window where breaking the line of sight will allow you to escape.
The gun is your last resort
There are so many exotic ways of killing your targets in Hitman that using a gun seems a bit uncouth, but it also forms bad habits and has the potential to cause more problems than it solves. Firing an unsilenced gun is never encouraged, but unless you hit a headshot you're unlikely to take down anyone first time even with your suppressed pistol. If the target shouts for help after you wound them, you're in big trouble, so leave the gun: 47 is just as deadly with his hands anyway.
Complete as many challenges as you can
Hitman has a new 'Mastery' system associated with completing challenges: the more you complete, the more you unlock. Weapons, items, and even mission start points can be earned, so if you want to begin your hit dressed as a palace guard, or acquire a special sedative, or even open up spots on various floors where you can retrieve smuggled items, then get on the challenges.
Stuck? Challenge icons contain clues on where to go and who to kill
If you're finding it difficult to get close to your targets then open up your inventory and scroll to 'Challenges'. From there, select either 'Assassination' or 'Discovery' and you'll see a list of places, people, and items which can be used or exploited to get ahead. Each of these is illustrated with an image, all of which will give you a clue as to what to do next.
Money is crucial
47 may be heavily armed, but perhaps his most crucial weapons are the coins he can take into the level. These coins are thrown to distract NPCs, and work maybe a little too well: they'll almost always cause anyone close to investigate, leaving you free to sneak past. They can also be used to separate targets, enabling you to take out their bodyguards.
Know your alert phases
The AI in Hitman isn't the brightest, but it's also (for the most part) not dumb: there are various alert phases you'll need to know how to handle. Being seen skulking around doesn't always mean a gunfight: Trespassing will see you escorted off the premises instead, as long as you comply. Your minimap will tell you what phase you're in: Compromised means someone saw you perform an action, and Searching means exactly what it sounds like. That said, the Searching phase can be exploited: turning on radios, flooding sinks and other environmental actions will see the AI abandon its post to investigate, leaving an easy way in.
Leave no evidence
An obvious one: don't leave people you've killed or knocked out lying around. But this also applies to weapons: if anyone sees a subdued guard's gun on the floor they'll either call for help or remove it themselves, potentially ruining a run. On the other hand, weapons can be deliberately left to ensure guards are distracted.