This sounds pretty hard, however there are some extenuating circumstances:
General tips- You DO NOT have to get all of the insignias in the same playthrough of a mission. Meaning that if you want, you could go for one insignia at a time, and it would still count towards the achievement.
- There is NO time limit (except for the "Swift" insignias), so you can take your time with most of them
- AFAIK there is NO penalty for choosing an easier difficulty (it's still perfectly doable on Goblin difficulty though)
- There is NO penalty for save scumming
- The game stores your three latest quick saves, making it easy to backtrack if you saved in a bad spot
- There are skills you can buy that make some insignias a LOT easier
- You can respec your skills at ANY TIME, allowing you to make builds for getting a specific insignia.
Insignia synergiesThe easiest combinations to go for are Thief + Shadow in a first playthrough, then Swift + Mercy in a second one (since kills cost valuable time anyways).
Shadow insigniaJust make loads of quick saves and reload if you get spotted.
Mercy insigniaJust don't kill anyone, you brute (except for "kill" mission targets that is, those don't count).
Thief insigniaIf you're having trouble finding the Thief tokens, you could use a guide, or you could play far enough into the story that you can buy "Greed", the Ultimate skill in the Perception tree, which just plain shows you where the tokens are when using Amber vision.
Swift insigniaThe most difficult insignia, which require you to find a good path to the objectives. With the exception of a few levels, the time limit is fairly generous though.
Again, there's no penalty for save scumming, so make manual saves whenever you're positive that you made a good path, and use the quick saves and reloading while trying to find a good path. If you completely botch a mission, you can both restart the entire mission as well as just restart the current zone from the menu at any time.
Invest heavily into the "Stealth" tree, more than anything into making invisibility last as long as possible.
If you're not going for Mercy in the same run as Swift, you can buy the Amber dagger from the alchemy tree, which will give you a point of amber for every kill. Paired with having stealth maxed out, this means you can be invisible and undetectable while performing a kill, as well as getting some of your amber back.
In missions where you're required to perform a kill, perform a kill undetected, or steal while undetected, with a maxed out stealth tree it is possible to just go invisible and perform the action. You might need to try it a few times, but it is possible to be "undetected" simply by being invisible.
*** Spoiler - click to reveal ***Completing the story and collecting all of the Quartz crystals, also opens up a skill which slowly fills up amber while you're not consuming it.
Good luck!