The easiest way to be safe is to have nothing that anyone with the power to take it from you wants.
To that end, this solar system is unusual in that it at one time had a number of planets in non-planar orbits. Back in the day, from a distance, it sort of resembled an atom, with all the different planets having its own plane of orbit. But that was then, and this is now. And sadly, as it is now, all of the non-habitable planets in this solar system have broken up; they're now asteroid fields. Asteroid fields which are known to be actively mined by automated mining systems that don't always recognize the difference between an asteroid and an unknown foreign space craft. Getting in without the teleportation you can block is therefore tricky.
Your civilization has long since mined virtually all of the usable resources of its single inhabited world. Its mining efforts are now in the various asteroid belts. And in case you're curious, it's not coincidence that the other worlds and moons have been converted into bodies with much smaller gravity wells, to optimize the efficiency of those operations. It's also not coincidence that a couple of those asteroid belts appear to be of significantly different compositions from the others, almost as if some other civilizations lobbed planets at yours, and your nation managed to deflect them and break them into bits.
Note that all of these mining operations have not resulted in your planet having a mass of highly refined readily accessible materials, apart from its battle and mining fleets (which are difficult to tell apart. There are some rumors around that there is actually no difference, that your battle ships can disassemble enemy ships to salvage their material resources at least as efficiently as your mining ships can mine asteroids. You, of course, know this to be false. Those two fleets use totally different logos. Also, your mining fleets would be hard pressed to disintegrate a planet into an asteroid field.) The reason for this discrepancy is that your nation exports a lot of goods. Goods which include war ships whose weapon systems are carefully chosen to pose no threat to you, but plenty of threat to less technological sides, and whose defenses are easily overcome by your ships.
Additionally, the overall environment on your homeworld is, from the perspective of most other races, toxic sludge. Building up to an advanced civilization such as yours has its costs, and you've paid yours. There are parts of your planet that are habitable, but in general, one needs to teleport into them. I seem to recall you indicated that you have a local lockdown on that technology, yes? Your world also has some rather nice space stations.
You are a strict importer of food and a net exporter of most other things, especially anything which can be derived from the toxic sludge your planet is best known for. The official report on your planet's overall health is that nothing grows there, so all of your food needs to be imported from off-world. In reality, very little will grow on the surface of your planet, but in the vast labyrinth of tunnels and underground cities wherein the vast majority of your population lives, hydroponic farming is a booming business, providing most of the food your civilization uses to thrive. But this population center and everyone and everything in it are your nation's best kept secrets.
As you are very concerned about
attacks from outside threats to your food supply, your nation has a strict neutrality. You do not initiate attacks outside your solar system. You do not trade significant arms or battle-quality medical supplies with any faction you publicly know to be engaged in a war.
(To speak plainly, while you are very interested in giving aid to other nations who you feel support your interests in their wars, you take pains to not understand that they are at war, ever. If some side forces you to be aware that there is a war going on, you cease all obvious aid to the side you support in the war, while supporting them in any very discrete manner that you can clearly get away with. For example, by supplying them with civilian goods that are surprisingly useful in military situations. Like, maybe, automated mining ships - but not your automated mining ships. And probably through other nations that also support your interests, rather than directly. Also, whenever you do go to war yourself, you use ships that are at least made to look like those of other nations. Mostly ships that you took as trade ins on space ships you sold, with everyone understanding you were just going to melt them down for their raw materials, so battle damage didn't matter and stuff.)