Is it easier to solo the levels? Do they dynamically change the number and difficulty of the mobs depending on how many players there are? I only tried one thing solo, the Tower 1 key thing and got wiped during the first wave I think.
I honestly don't know how the game scales, if it even does.
But some rules of thumb I use, and I do solo a lot.
* The best missions to solo are Extermination, Sabotage, Deception (if you've got a solid secondary weapon, as you won't use your primary while carrying the datamass), and Rescue (though you'll need to be on your toes to make sure the VIP survives).
* For all of the other missions, join an online match or play with friends, with friends being the preferred method overall whenever possible.
- Capture missions are much harder than they might seem at first, as you need to work together and be ready to sprint to take down the target. There are two targets though, and you only need to nab one. Once you do enough damage for them to drop, go over and hit (o) to capture their essence or whatever the fuck that's supposed to be. The player that does this will get a nifty little glow to em, so that's nice.
- Survival missions are all about controlling the oxygen supply. Once you set the alarm the air will begin to deplete and there are two ways to mitigate that - one is to activate the resupply drops that the Lotus tells you about or take down enemies as each enemy has a chance to drop a small air unit. The lotus resupply canisters provide 30 air, so I'd recommend waiting until 65% oxygen before activating one (30% air from the canister + a little room for any pickups that other players are grabbing while you activate it). The enemy air drops are good for 5 air I think. At five minutes you can exit the mission, but the longer you stay the more rewards you get
at every five minute interval. Set yourself a goal to reach (like 15 minutes for example) but be ready to bug out if you're running out of air. There's an element of luck to these missions in that sometimes enemies will not drop enough oxygen. NOTE: If its an *Alert* Survival mission there are no additional rewards after 5 minutes, so just extract at that point.
- Defense missions are straightforward. Protect the artifact from waves of enemies. Every 5 waves you'll have the option to extract or keep playing. The more you play the better the rewards, and they keep stacking up, so by wave 15 you've won a wave 5, wave 10 and wave 15 reward (I might be full of shit and you'd only get the level 15 reward). You do not need to extract to keep these items. If the artifact is destroyed on wave 16 you still keep your rewards up to that point. The only way you lose everything is if you end the mission by aborting or via forfeit.
* When looking at enemy level ranges, compare those levels to the level of your warframe. The levels give a decent sense on how much enemy damage is going to come your way, so if you play levels 10 levels above your warframe, expect to get hit hard, and don't be surprised if you need to expend a revive or two.
As far as the damage YOU can dish out, that's a bit looser. I've been able to take down level 25 enemies with level 5 weapons provided the weapon was strong against that faction (like piercing vs grineer) and I was hitting the enemy weak spots. But a general rule of thumb I use is to keep weapons within 5-7 levels of the enemies, though add 10 to that range if you've forma'd or polarized your weapons.
* You get 4 revives per day, PER WARFRAME. So if you've used up all of your Excalibur's revives, switch to another frame and you'll have four more to use.
* When it comes to spending platinum, its extra slots for weapons and warframes that you'll need to spend platinum on. Besides the purely cosmetic stuff like scarves and colors, everything else in the game can be acquired through play.
* As soon as you can in the early going, slot the mods Redirection (extra shields) and Vitality (extra health) in your warframes. Your survivability will go up dramatically, especially if you upgrade those mods. So, upgrade those mods!
Just some quick tips. Hopefully this helps a bit.