Another run, another win. This time, after quite a few wins behind me, I've decided to clean the entire map and prepare a proper defense for the endgame. Being capable of starting with 2 Sevastopols is something else. There are a few things that I've noticed that can propably help new players that should be the priority, so I'll line them up right now. Now I can, without doubt, state that I've finished all the "endings" the game has to offer.
First, you should not start with too many ships. The flagship and 1-3 lightnings along with a tanker for each lightning should be enough. There are more than enough ships to get later in the game, and every single ship in your fleet burns a lot of fuel, best to keep the fuel efficiency good.
Hidden cities can be found on your own, without the use of land radar, although it can help quite a bit. You want to zoom in as far as possible so that you see the actual terrain around you, then look for roads going from cities into the middle of nowhere. If there is a large gaping hole surrounded by cities, there's propably a hidden city somewhere in that desert. You just have to look for it, and the best way to do that is to follow the roads. Winning the game without hidden cities is really, really hard since any mention of your fleet in any official city will lead the Strike Groups right to your location.
Don't engage strike groups, they're not worth it. What you want is to pelt them with airplanes and missiles whenever you locate the SGs. A non-nuclear cruise missile is 1500 gold, repairing your cruisers after fighting an SG usually exceeds 20000 gold and takes a lot of time.
Nuclear groups and aircraft carrier groups do not migrate. They're the same as garrisons, just with the capability of pelting you with aircraft/missiles. If you've destroyed all the SGs, you don't need hidden cities anymore.
Garrisons, including nuclear groups and carrier groups, will chase you if they think they're stronger than you. They won't go to the next city over like that since they don't have enough fuel for that, but they can chase you down till you're out of fuel if they think they're stronger than you.
Nuclear groups and carrier groups do not use their radar unless they're expecting you. This can be used to strike a garrison with these in the middle of the night, making their main advantage useless if you take them by surprise.
Nuclear groups and carrier groups are almost in every second city next to Khiva if you play on normal. If you are detected when attacking a garrison next to a city with a NG or a CG, run. The loot is not worth losing your strike group.
Hoard A-100s and AA missiles. The enemy is physical, they have a limited amount of resources to throw at you. You can take down enemy missiles with A-100s and with AA missiles. You can also take down enemy plane squadrons with A-100s and AA missiles, although using A-100s against planes is not recommended due to the high cost.
Use AT munitions. While I've finished the game with basegame vehicles without using special munitions, AT shells can make your Lightning useful not only in early and midgame, but also in the endgame. The rest of the munition types are either too expensive or not effective enough, but a Gladiator with AT shells can take down an SG on it's own with a skilled pilot.
While decoding enemy transmissions is fun the first dozen times, it gets tiresome quite fast. Once you've destroyed all the SGs, leave a light corvette in every intelligence outpost. Knowing where enemy NGs, CGs and transport convoys are is crucial to minimizing loses and maximizing profit.