Assuming you can get to depot A quest (find drill parts) without any major issues, there is a HUGE shortcut you can take as a stealth build by just skipping pretty much all of depot A:
https://www.twitch.tv/videos/398609044And then you just open up the rest of the map and go collect oddities from trash bins (lockers, boxes, under rocks, etc, etc) in and around every major hub (Core City, Foundry, etc). That will get you 2-3 levels right away practically for free. As you go collecting oddities, you also shop for new equipment.
At that point you are 3+ levels higher and with much better equipment and can go back to depot A and breeze through it getting all the oddities you missed initially.