Gears Tactics has an efficient tutorial: After the first mission, you should understand most of the tools at your disposal, like overwatch, frag grenades, and the Lancer rifle's unbeatable chainsaw. It's an easy game to dig into, but it's also hiding some cleverly complex tactics and important differences from XCOM that aren't obvious in its early hours. In hindsight, these are the tips we wish we'd gotten before we started playing.
Here's what you should know before you jump into Gears Tactics.
Losing a hero on Ironman instantly ends the campaign
Gears Tactics is generally easier than XCOM, but there's a crucial difference in Ironman mode, where the death of any "hero" character will immediately end your campaign and delete your save file. When you're deciding who should draw enemies' overwatch shots, maybe throw one of your replaceable soldiers at the problem instead of Brave Protagonist Gabriel Diaz. Gears Tactics provides plenty of leveled-up, generated characters between each mission for you to replace anyone who's died.
Sliding into cover extends your movement range
Just like in the Gears shooters, your soldiers in Gears Tactics can body-slam into cover from a few feet away, like they're being pulled into place by a giant magnet. If you pay attention to your movement range in Tactics, you'll notice that the cover magnetism "cheats" a little bit by letting you reach spots that would otherwise be just out of range. Look carefully before you move and see where you might be able to eke out just a bit more distance—sometimes even a small change can make a big difference to the enemies you're able to hit, or afford you a spare action point to spend on overwatch.
Overwatch works differently
Unlike XCOM, you can take as many shots in overwatch as action points your character has remaining at the end of a turn. Overwatch also triggers if an enemy takes an offensive action without moving. Instead of taking a low-percentage shot at an enemy in cover, discourage them from moving or acting by covering them or a key chokepoint with overlapping overwatch fields from multiple units. Note that some of Gears' AI, particularly the explosive Ticker enemies, do a good job of avoiding overwatch fields-of-fire. Also keep in mind that critical hits can't be scored in overwatch (an unlockable ability on Snipers is an exception to this).
Use Redeploy to keep your Heavy mobile
Heavies are valuable defensive gunners. They're made for hosing down advancing enemies with their wide field of overwatch fire. Later equipment upgrades let them carry tons of ammo, and the late-game Ultra Shot ability lets them empty an entire mag until an enemy dies. Dodge that, buddy.
Heavies can move and shoot, but they're at their best when firing from a fixed position as long as possible. With each shot, Heavies build a stack of Anchored (accuracy +10% and damage +15%), turning them into shredding machines after the second or third shot. There are different, valid ways to build a Heavy, but for me, maintaining these stacks as you reposition was crucial: Hit Redeploy at the end of a round to move a Heavy 3 AP without losing Anchored.
Proximity Mines close e-holes
Uh-oh, the map has sprung a leak: an emergence hole—a subterranean pit from which enemies pour out continuously until closed. Normally you have to wait until after a wave of Locusts pops out one of these evil potholes before sealing it closed with a grenade. But what Gears Tactics doesn't tell you is that you can pop a Proximity Mine (an unlockable Scout ability) on top of an unopened emergence hole to not only close it when it tries to open, but kill every enemy who was about to emerge. There's even an achievement for this.
Reviving a downed character gives them 3 actions, while self-revive only gives them 1
When one of your squad is bleeding out in Gears Tactics, you need to act quickly to revive them because the Locust will execute them after a turn or two. When you have another squadmate close by, it's better to use the revive ability to help the downed Gear to their feet. This will grant them all three actions they'd normally start their turn with. Once per mission on lower difficulties Gears can use a self-revive ability to stand up without help, but they'll only have one action this way, and it won't be available if they get downed again. Save self-revive for dire situations and use the teammate revive ability whenever you can (also, know that self-revive isn't an option on the two harder difficulty levels).
You can use the quiet time after completing an objective to wait out cooldowns, but don't wait too long
Later in the campaign, many of Gears Tactics' missions involve fighting your way to a gate or a bridge, then opening it to proceed to your second objective. Once you've cleared out all the Locust in the area, wait a few turns before walking into the objective circle. This can help you refresh some long cooldown abilities like grenades. But don't sit around for too long—I tried this trick a few times, and once the game dropped some fresh Locust on me after I'd idled for three turns. Take a breather, not a nap.