Just a quick nothing special guide I'm making because I've seen half a dozen+ threads about difficulties with armor/shield guards and how far away AP weapons are from the start.
If you've watched the trailer, you already know one way, but it required a device, it can be done with less. If there are unprotected guards, you likely only need a wrench. Otherwise you need a gun. It's not difficult to get either before encountering armor/shields so I'll assume you have a gun.
Wrench: Knock out someone and steal his gun. Otherwise bring your own (preferably silenced).
Before you board the ship, did it have spotlights around the outside (avoid these, or your pod will get shot). If it did, then that means the ships has windows. Otherwise you want to find fuel drums.
Window (it's less destructive):
Bring the guard to the window (e.g. let him spot you, or improvise), then hide in a corner where he can't see you. When he spots you, shoot the glass. Then either use a device, or get your pod to pick you up. You can only do this once per window so try to get as many guards at once.
Fuel Drum (ship may break, but it's fine):
Bring the guard to a fuel drum, make sure you are not in the same room as the fuel drum, and shoot it. If the ship breaks in two, it's fine, you can still board either part by moving your Breaker pod between the airlock and any holes you make. I don't know whether Shield guys can actually survive this but if it vents them they should die. Armour guys get obliterated.
Pickpocket & evade:
Finally this one. This doesn't actually kill them, but it's just as effective if not more so than the above methods, since you don't have to kill every guard to complete your mission, you generally just need the keycards. You can practice this method as much as you like in Practice (Hard) without repurcussions. Important!: Also it goes without saying that if the guard in question has a keycard, DO THIS FIRST. Nothing is worse than venting a guard who has the keycard you need to proceed. If that does happen... improvise, or always bring a key cloner and use it pre-emptively.
??? (many booms):
This one involves TWO or more ships. Have fun discovering it. Tip: It helps if the mission only requires Assassination. There's another guide on this one already so I'll leave it blank.
Hope this helps. I left this guide to basics because part of the fun is improvising. There are many, more ways to kill AP/Shield guys without AP weapons by using devices and you can improvise to improve on the above methods in their basic form.
Here's a list of devices that can assist with killing and getting away safer/easier, but it's basically every device, you can improvise. Maybe later I'll add a second part with different ways of using devices but I don't think it's necessary and not immediately after game release. I just got the game myself and don't know as much as beta players. I could add screenshots, but you can quickly recognize the window rooms once you know to look out for spotlights on the exterior.
- Crashbeam (shield only afaik)
- Key Cloner (key preservation if you're going to vent the owner)
- Sidewinder (all)
- Slipstream (all)
- Subverter (all, yes it can help with armour but only - sometimes - if turret )
- Swapper (all, watch trailer)
- Visitor (all)
Possibly more that I missed.
If you're still having problems, then it might be that you have to use more devices and/or stealth. With a sidewinder and a slipstream you should be able to overcome most problems. Even with no devices you can still press F to fast forward and wait for the guard with the most annoying LOS to go on an errand and then slip past.