Current worth

Some of the missions really are tough ... until you figure them out.

One way to survive some hard missions is to fly around the edges of a battle and let your friends do the fighting. Not very courageous, but you survive!

Also, watch for that "incoming missile" warning. Start dropping countermeasures, intermediate or advanced countermeasures if you have them. A hit when your shields are down will take you out. So will a mine, no matter what ship you are flying.

Upgrade your shields and weapons whenever you can. Do the same with your ship.
The irritating thing is when you click on Juni or King to see what kind of shields or weapons they have ... and realise they are carrying much better ones than their ship is supposed to handle. The game is a bit biased in their favour.

Another tactic ( an old one that does work) is to focus on a ship comming at you, that is not selected the current target, you will not have missle lock, but they pester you more than the selected target. Another one I found on my own, I call it 'Backup & Be-gone' , as your selectet target is approaching & attacking, engauge reverse engines, firing all forward weapons, and let loose missles w/ selected target is within 800m.

There's a neat little trick/exploit that can let you level up faster without much effort in SP- buy a whole lot of cargo at a low price that is worth a significant amount elsewhere. Your current worth is calculated based on the best price you could get for your current cargo, rather than how much it was worth when you bought it. This doesn't always work, but if you're close to a level it can save you quite a bit of time.

Also, tractor everything while on a mission. Keep an eye out for the loot icon at the bottom of the screen and hit tractor all (B) every time you see it. After each battle, you can take a quick stock of what you've reeled in and make room for more valuable stuff (H-fuel is a pretty common drop in SP, especially when Rheinlanders show up, and is worth a decent amount in most places). You might already be doing this, but if you're not then I highly recommend starting- it will almost always take a chunk out of your next level before you even reach it.

Also, like others have said, avoid the use of ammunition-based weapons if you're having money trouble. Countermeasures are dirt cheap, so they're not much of a problem, but a full load of decent mines or missiles could easily cost you as much as your next level- or as much as some new ships. As for shield batteries and nanobots, don't use them unless you absolutely have to- even if your shields go down, try your best to evade until they come back up and only use batteries if you keep taking hits. Likewise, only use nanobots when you're on the edge of death- it is almost always cheaper to repair a ship on the ground than it is with nanobots.