You can win the game without a single terror mission - you can skip them as long as you can handle the score drain (and you can). Yep, just arrive and abort tough missions until you're ready.
Also, pay attention to radar coverage and airgame - terror ships ain't too hard to take down.
Big turrets (and sectopods), like those in terror missions, can one shot overkill (leaving no corpse to retrieve and repair) any armor, including tanks and sectopods. To deal with them, use cover, smoke, throwable / arc weapons (sharpnel charges, mortars), PSI puppets / expendable targets / meatshields.
Then play as it goes. In many places, game got easier compared to years ago. Generally, when played "properly", mid-to-late game is harder to lose troops than early game. Yet, you can lose (lots of) troops and still win, it's fine. Shield elites with meatshields / dogs - it's entirely possible to beat the game at ironman / superhuman without ever losing these two or three soldiers that you really care about.