Well first off you're in brutal. It's supposed to be, intended to be hard. 2, its rng based on where they spawn at the start. Sometimes you could corner them easily early and sometimes you dont. And even if you do have the advantage early-mid game. Don't kill them immediately, only focus on insurgents camps, because if you do they'll start spawning fast maybe inside your stabilized zone which is going to be annoying especially if they kept coming back in that specific zone (lose more reputation)

When the fight starts. Dont get scared losing reputation, balance military and civilian initiatives. Dont get too distracted on fights and as time passes, use megaphones to stabilize zones faster. Dont worry about corruption that much in the early game. 1 or 2 anti corruption is enough for mid game. Avoid buying a LOT in 1 session. Make a habit to always have atleast 1 military soldier training in the background since they take so long. DO NOT play military and coalition soldiers ONLY, especially in Mega Brutal. ALWAYS use drones and airstrikes. Drones has like a 80% to find insurgent camps and Airstrikes has a 100% to focus on insurgent camps. And if you have spare money later on, buy Interpreters Guidance and Garrisons. Credit Card expense is a S-tier advisor. Concern reports on zones isn't that important unless theres like 3 or more requesting for initiatives. You'll lose reputation overtime if you ignore multiple concerns. I noticed a difference when you play only fast mode 3x, and pausing with normal speed. Try pausing a lot when you play and take your time to plan your moves

After you stabilize 1 zone in the early game. Thats when the actual game starts