When you visit Griffa early on, upgrade Max's Volition, which will add bonus scrap when looting enemies and scavenging sites. It doesn't add much bonus scrap at first, but it'll increase as the upgrade is leveled up

There's a limited amount of scrap in each camp, but aside from reducing threat in an area, the best value of taking a camp is gaining its resources. All allied camps will periodically (about every 20 minutes) deliver scrap to Max. Each allied camp gives 20 scrap. You don't need to do anything to collbect the scrap, so this is one of the better ways to gain a steady income.

(Glitches out often. You will sometime get no scrap from some allied camps. I have 14 camps cleared and yet I'm only geting 60-240 scrap per delivery instead of the 280 it should be, on top of which it only delivers every great once in awhile, if at all. So expect to get shafted at some point. No idea why it's doing this. Sometimes reloading a saved game fixes it but not always.)

They're rare, but Scavenger Encounters offer a small chunk of scrap. After inspecting an area with the Vantage Outpost, check your map and look for encounters. The Scavenger Encounters are marked with a little scavenging hand. You'll get 50 scrap from the Scavenger, but you can kill the person to get another 50 scrap. Be sure you talk to them before you kill them or the scavenger won't drop scrap.

Don't fear the storms; embrace them!

Track down the scrap crates flying through the storm on your minimap, park the Magnum Opus in a defensive position, and jump out and destroy the crate. Breaking a crate against a wall is ideal so that the scrap pieces don't go flying everywhere. Crate locations will stay on your minimap after the storm has passed, but will vanish if you walk/drive far enough that they go off map.

Roaming the Wasteland are Scrapulance vehicles, which are part of the Scrotus Enemies faction. These little clunkers are worth a ton of scrap if they can be caught. Chase them down, kill the driver, then drive the vehicle back to a Stronghold to reap the rewards. The amount of scrap varies, but often totals to a few hundred scrap rewarded. If you destroy the Scrapulance, you'll get less than 50 scrap, so be careful with it! Known Scrapulance Locations:

• Gasworks camp in Blackmaws region
  
• Hollow Point camp in Balefire Flatland region
  
• Roaming Dry Gustie region by the convoy route
  
• Overlook camp in Grit Canyons
  
• Gob Stone camp in Grit Canyons region
  
• The Choke camp in Grandrise Region
  
• Please add scrapulance locations as you find them

A tip for scrapulence in the comments;

Originally posted by Team Vladof:

Storms ... if you can find a large rock wall or structure to park near, park behind something that blocks the wind (or under something to block the lightning). If you wait the storm out, chances are good you'll see boxes on the map that got stuck on the structures around you. Doesn't work out in flat, open desert, but over by the piers/docks, ravine areas, etc. Wait out the storm, then go collect your scrap. I'd almost always get at least 2 boxes this way, but got 4 boxes from one storm one time. Def helped, b/c I was working my way up the V8 chain at the time.

Scrap Pallets are rare, but they're a great find. Each Scrap Pallet awards 50+ scrap. Here are the know locations of Scrap Pallets:

• Dry Gustie Vantage Outpost
  
• Scavenging Location just south of Griffa's spot in Dry Gustie
  
• Feel free to add where you've found Scrap Pallets

Take time to build up the Cleanup Crew Project in each of the Strongholds. The crew will automatically collect scrap from vehicle fights, so gathering the scrap from destroyed cars is much less tedious and you have more time to drive off and find another victim.

Another valuable project in the Strongholds is the Survey Project. This will reveal all interactive locations in the region, which is helpful for when you're out hunting for scrap.