Strategy (Long War)
Long War's economy is very different to vanilla. While launching satellites will increase your income, satellite spam is not the answer to all your problems like it is in vanilla. Satellite uplinks give only one satellite per uplink plus adjacency and satellites are more expensive, so the cost of increasing your satellite coverage is much higher. The extra income you gain from each satellite is lower, since a country will already fund you 50% without a satellite. Your satellite network must be protected by interceptors, and interceptor maintenance is expensive - in fact it's likely your single biggest expenditure each month. Even with good interceptor coverage, eventually the aliens will get annoyed enough to send battleships after your satellites, so you will need to occasionally replace them. With all of these factors combined, launching more satellites will only marginally increase your income. You can improve this aspect of your income by thinking about efficiency - cover high income countries and cover whole continents to improve the efficiency of your interceptor placement. Prioritising aerospace research will also help, since it will allow you to reliably shoot down UFOs with fewer interceptors and less damage taken, meaning less interceptors needed and less maintenance.
A large amount of your income will come from the sale of alien artifacts. Long War presents you with a lot of missions, which means a lot of alloys, elerium and corpses to sell - chances are you'll have considerably more of these things than you can sensibly use in the early game. While satellites don't give you so much direct income, the extra UFOs you can assault with more satellite coverage will mean more artifacts to sell, and hence more income indirectly. Do not sell things on the Gray Market until you need the money, because you never know when EXALT is going to hack your funding and steal a portion of your funds.
In fact, with the Foundry projects that increase the amount of Alloys and Elerium you recover from raided UFOs: if you can confidently do so with regularity, particularly with landed Barges, selling the two can be an extra means of income. And with an array of Workshops giving you refunds on them on projects, it is not too difficult to reach a sustainable balance between selling and using, even with the occasional Council request giving additional personnel and credits in exchange.
The amount of Meld that you get from canisters scales with how well the aliens are doing. As such, you may find that Meld becomes hard to come by if you're doing "too well", so selling it or giving it by Request should not be done. On the other hand, if the aliens have you on the back foot, you may find yourself with enough Meld to build plentiful MECs and gene mods to help you get back in the game.
The two main sources of panic in the Long War are Terror Missions, where an excellent mission rating only minimizes the Panic raise that will occur, and public UFO sightings in Council Nation airspace.
For satellite coverage, since Uplink and Nexus capacity has been halved, you'll need more to fully cover all Council nations. The ideal satellite facility configuration is now a 2x3 block, with 3 Uplinks and 3 Nexi; this will allow you to cover all 16 countries. While at first you will lose at least 1 country, and have only 15 countries to cover at start-- though you can liberate the 16th; in fact, liberating at least one country is required for story progression, as any withdrawn nation will spawn an Alien Base within it's borders-- you should build with the 3 and 3 in mind, so that you will not need to rebuild later, if your aim is to rescue all member nations.
Still, coverage as soon as possible is ideal, so you can manage any smaller craft that come into covered airspace, and assault landed UFOs that are too big for your interceptors, or at least harass them in-flight. This (ineffectual) show of force is at least good PR for the Council nations, as doing at least 50% damage to UFOs reduces both Panic, as well as slows the aliens' research progression. Try to keep some satellites in reserve, for when the inevitable Battleship comes for your satellites. Well, if you have the money, that is.
Story progression is nearly identical to Vanilla, except that a satellite must be put over a withdrawn nation (be it that first one, or one later lost to Panic), along with a skeleton key being built. Any further countries lost will also spawn bases for additional assaults (and while difficult, they have been made profitable, to give you a fighting chance to bounce back from severe panic conitions).
Due to the fact that aliens can now conduct research themselves, it is recommended to have a general direction towards which to focus your efforts in order not to fall too far behind them and avoid researching projects that may not prove immediately necessary at the present moment.
With the way fatigue and injury are handled in Long War, armor becomes a much more valuable asset to your troops as only hits that manage to successfully penetrate a soldier's armor can grant him a vacation in your sickbay. Skipping Laser Weaponry entirely is not recommended on higher difficulties unless especial care is taken to maximize scientists through Council Requests and Satelite Coverage in addition to having a healthy amount of laboratories, as the both the accuracy bonus and damage are highly desireable in the early stages of the game. Even later on, handing a Rocketeer a Laser Carbine may even be better than having him use advanced weaponry as this improves his ability to hit bullseye with his launcher and results in less scatter.
Furthermore, it is very important to put research effort into your airspace capabilities if you wish to preserve your satellite coverage. When given the choice whether to buy additional Interceptors or upgrade existing ones through foundry projects, weaponry or even temporary boosters, it is almost always recommended to go for the latter. The more UFO's you are able to successfully shoot down with your Interceptors, the more materials and money you will be able to salvage in the long run.
The pace at which the aliens conduct research is dictated both by difficulty level and player action. Soldiers that are MIA (left behind) at the end of a mission will significantly boost alien research and should at all times be avoided unless if by doing so more are likely to meet the same fate. As of Beta 14, this will still be in effect, albeit in a much lesser fashion (1/4 of its original value). If you lose a soldier but win the mission, the aliens don't get research.
They don't gain research for shooting down an interceptor.
They don't gain research for shooting down a satellite.
They do gain a little research for each non-air raid UFO that escapes undamaged.
They have a chance to gain a little research if a UFO escapes lightly damaged.
They gain a good bit of research if a landed UFO on a research mission is not defeated.