This guide will help you obtain the following achievements:

See my vest
Obtain 5 power armor skins


Banker
collect 60,000 coins


Tacticool
Fully upgrade a weapon brand


Gear Head
Obtain all improved weapon upgrades

Active stealth at 00:31
Deactivate it at 00:35
Activate it again at 00:41

(You might have to toy with this a bit if you don't have all stealth ability upgrades)

As you level up, you will get more coins from clearing each section in stealth mode.
Feel free to leave a comment if you have any questions.