Tactics (Long War)
As many other XCOM titles, there are no right or wrong way to play Long war. What works for you in the tactical combat, might not work for others and vice versa. There are some subtle changes to the way that Long War plays, from Vanilla, but most of the some basic gameplay ideas are still in effect. Some changes however are very profound and changes the way that the game is played in drastic ways.
The following list is in no way intended to be exhaustive or complete, but instead shed some light on the nuances of Long War.
Long War Combat guide and tips.
Pre-battle Guide & Tips
This covers general advice, when setting up squads, unit compositions, class synergies and other things that are important to consider before heading into a battle.
Map Description
A new feature in Long War, is the ability to see what kind of map you are going to. You won't know exactly what map you are getting, but you will get a general idea. This information is incredibly important, as it gives you an idea of what type combat scenario will occur. For example: A Long Road road with vehicles. Notice how it doesn't say what map it is, but you can make a reasonable assumption of what type of soldiers that you should take with you. These Map hints, can make your battles easier but be careful, they can sometimes be very misleading.
Squad Composition
When putting together your squad, first see what sort of terrain you are fighting on, then what mission it is and then try to adjust the class choices to whatever specific playstyle you prefer. For instance a very aggressive player might want to take one mobile sniper, one rocketeer, two infantry and one scout and assault with him, so he can constantly move forward against the Alien positions.
There is no right or wrong way to set up the squad. Usually though, if you can see how the different classes compliment each other, then you have a pretty good set-up.
If you have specific goals in mind for a particular mission, like capturing an outsider, then you should always plan according to that objective. As you want to make that process as painless as possible, while still being able to handle whatever else the mission throws against you.
General Advice & Tips
This section covers anecdotal or general concepts and tips that might not fit into any of the above, usually just player specific styles or advice that might help you set up the perfect team.
MEDIC! A medic is one of the most useful classes to have around, they can keep your soldiers healthy during battle and they increase the survivability of friendly (and enemy) soldiers with their smoke grenades. I personally always take one with me during every mission.
Divide and Conquer Usually it is never a good idea to split your team into two, but on urban maps, there some merit in doing this. When you have both your Squad upgrades, you can split your squad into fire teams of four people. Why is this a good idea? Because it lets you breach buildings and other structures much more efficiently and sets you up for more flanking maneuvers. It also lets you get out of deadlock situations where you are in a prolonged fire fight with Alien opposition, without any opportunity to move forward.
S.H.I.V all the things I liberally use S.H.I.Vs, they are much better than the standard rookie, can take more damage and can create moving cover. They might not get any experience and be less effective than a regular soldier, but they can be outfitted to oblivion due to the much expanded S.H.I.V tree, present in Long War. They also add the benefit of making me feel less sad when checking out the memorial wall, which by the end of the game is quite big.
Battle Scanners. Seriously. Battle scanners become a requirement when seekers start coming into the enemy squad rotation as they can seriously wreck any well laid plan. Seekers have had many shackles taken off their AI, so 4 seekers can decloak and strangle you in one turn unless you do something about it.
Combat Guide & Tips
This part of the guide covers the tactical decisions and manuvers that you can be faced with during battle.