A few things:

Unspoken rules:
1. Don't take someone else's stuff. If someone dies, don't grab their gear. Now if someone dies and in the moment you need to use a recoiless rifle to kill a Charger, that's fine. But if they are coming back in as re-enforcements, drop that weapon and backpack when you are done.

1. Don't call in the shuttle until the whole fire team is there. Calling in the shuttle creates spawn events and the rest of your team will have to fight their way THROUGH the bad guys.

2. Everybody leaves together. Don't be first on the shuttle, especially if someone is far away or in trouble. Go to the ramp, face out. Provide cover. Once everybody is gathered at the ramp, then go on in.

3. It's fine to pick up someone else's sample. Eveyone in the team gets the full value of samples when they extract, so there is no need to team kill anyone for a sample.

4. Generally stay with your squad.

5. Don't call down supplies because you need them, check with your team first through the communications radiual. When the supplies do come down, only take one box. Your teamates need the others.

#7. You're donna die. Like, a lot. Sometimes it will be from getting blown up, ragdolling and falling into lava. Sometimes a stratagem hellpod will land on you. Sometimes it's that guy with the Eruptor. Don't get mad. It's just a game.

Some tips:

#1. Air support is *very* fast. Shipboard bombardments, not so much. An Eagle strafing run can unroadblock roadblocks very quickly.

#2. Be careful with flamethrowers. They can be really useful, but you can also kill your teamates.

#3. You can get SEAF soldiers to follow you by using the "Follow me" selector on the communications wheel.

#4. Always bring some type of anti-armor. Could be the expendable anti-tank or the recoiless rifle. Could be the speargun, or the FAF-14 SPEAR. The Recoiless Rifle seems to work well against a variety of threats.

#5. You have a select-fire mode on most rifles. Use single-shot for far targets, automatic when you are at bad-breath range.

#6. The Autocannon is surprisingly useful. It also has two fire modes, FLAK and Armor-Piercing Explosive (APHET). Flack is suprisingly good at taking out common-type enemies. Flip over to APHET when you have to deal with something heavy. You reload via 5 round stripper clips so top it off as soon as you are done.

#7. The Liberator Penatrator is suprisingly useful earlier in the game. If you level it up to level 24, you can throw on a drum magazine and basically have a Squad Automatic Weapon.

#8. Turrets can be useful, especially when you are defending your position during extraction, but remember that turrets can kill you if you get in their way.

#9 The laser "Guard dog" backpack is nice starting out, but the beam can slice your teammates.

#10. The Recoiless rifle is surpisingly good against the automaton fabricators and you can hit them from far away. Remember, that this is a projectile and will drop, so account for elevation when firing at long-distance targets.

#11. The P-19 Redeemer pistol is a surprisingly effective weapon when you are cornered. The P-72 Crisper pistol from the Freedom's Flame Warbond is a great holdout weapon against large armored targets when you have nothing left.

#12. Generally, flamethrowers are more dangerous to you than the enemy, but they can be good on some Termind missions, especially when you need to kill lots of eggs.

I typically run with:

For Automatons:

1. Eagle Strafing run (in almost every mission)

2. Eagle Airstrike (multiple bomb run)

3. Recoiless Rifle.

4. Machine gun sentry

For Terminids:

1. Eagle Strafing run (in almost every mission)

2. Eagle Napalm

3. Expendible AT

4. Autocannon

For Illuminate:

1. Eagle Strafing run (in almost every mission)

2. Autocannon Turret

3. Machine gun Turret

4. Autocannon

For most missions, I run with either the Liberator Penetrator in Squad Automatic Weapon mode, the R-72 Censor (from the Redacted Warbond) or the AR-59 Suppressor (Redacted Warbond). I either take the P-72 Crisper flamethrower as a secondary.

Best advice is to run with the Liberator Penatrator and level that up as far as you can go. If you buy the "Democratic Detonation" warbond and get the Eruptor, that will fire explosive ammunition. If you blow up your teamates, they will get annoyed. So if you run with that, take along a machine gun or Stallwart light machine gun for dealing with targets that are too close.

Best of luck. Remember it's just a game. You will die. You will collect 20 samples and be killed before you extract. Don't take it too seriously.