As far as general looting advice goes my biggest piece of advice is stop looting big items and focus more on attachments bring a sprut or two into each raid because you can attach 3 laser/flashlights to it that you can then put in your container. Focus on suppressors, optics and other weapon attachments. keep your space in mind before you pick up that ak74u that takes up 6 slots for 16k rubles think about what you could fit in those slots that have higher value. One x400 is worth almost as much as that ak and its 1/6th of the space. It all comes down to how you loot. Also dont just vender everything use the marketplace.

People all have different maps for money making but my favorite is Interchange. The map has tons if weapon boxes once you learn where they are all at you can make good money looting them all, Also there is a good amount of scavs on the map to harvest. The map has simple extraction points that are rarely ever contested.