Ok, here's the deal. Sure, you can nuke them from your ship with dumbfires, or get in your SRV and try to take them out long range, but you'll never get better at ground combat like that, and you won't feel much like a warrior. I did it a few times at the beginning, but it's not much fun.
So here's my advice for a newcomer to these missions.
1) Get some pre-upgraded gear. G3 suits and weapons are easy to find if you go looking. Having at least a G3 suit will help your survivability. See thread here -->
https://forums.frontier.co.uk/threads/the-great-pre-upgraded-gear-sharing-is-caring-thread.576352/
2) When you arrive at the settlement in your ship, come in low and fast and land about 400m out, no closer than that, out past the landing pad is a good spot so you have a clear view of the settlement
3) When the dropships arrive, let them discharge the scavs and wait a bit until they settle. Use the camera suite to get a look at where they are.
4) Disembark and approach the settlement, keeping buildings between you and where the scavs are. Line of sight is very important, and the NPCs cannot see through buildings and containers and other cover. Stay behind cover.
5) When you get in range the NPCs will start to appear on your radar. This helps you locate them, and discern their patterns.
6) Turn on your shields before combat. They are OFF by default.
7) Never get caught in the open, and never engage more than 1 NPC at a time (until you have upgraded gear, anyway). Sneak around to get behind, and pick them off one by one. When you get a kill, run away again, staying behind stuff until you lose your pursuers.
8) If you can stay out of sight for a minute they lose track of you and go into search patterns. This is your opportunity to circle around and find one off by himself.
9) You can run back to your ship at any time to recharge/resupply. As long as it's at least 400m out, the scavs will not chase you that far. Circle around as needed to avoid them.
10) NPCs have a hard time hitting moving targets. Never stand still unless behind cover. If your shield goes down for any reason, run away, staying behind stuff, until it's back up.
Pro tip: If it's a restore mission, you only need to locate the PWR building, cut the panel, charge the port, then get inside. Often the scavs are not guarding the PWR building and you can do this stealthily. If they are near it, lure them away or kill them using the above methods.
Once you've restored power the base is open to you. You can run in and out of buildings to escape scavs. They don't have clearance and can't enter so you can pop in and out of a doorway to kill them that way.
If you need practice with your weapons and suits, do a few on-foot conflict zones (low ones at first). This will give you time to experiment and learn how your weapons and suits work, while having a team of NPCs on your side helping out.
These missions are loads of fun once you've figured out the NPCs patterns and how to use cover to your advantage. You'll get bounties and rank, too.
Have fun
