I've got all achievements in Halo Wars. I could help if ya want

1. As the mission starts, send your units up a little bit and spawn kill that spirit drop ship the immediately clear out the subway tunnel to speed up the mission. If you are only going for gold, turn on Fog, Rebel Supporter, and maybe Rebel Leader right before the last enemies are killed by the tunnel. Fog doesn't change gameplay and Rebel Supporter/Leader also apply to the Spartans, the transports, and the bullet sponges- I mean civilians. 2. Go around the map focusing on enemies in the sniper towers since no enemies will retake them. I don't even worry about resources until most of them are taken out. Micromanage and move your units, and plasma grenade on Forge's warthog = no bueno. 3. After the cutscene, make sure you move at least one unit by each base location and take both right away. I put a reactor on one and all the other building slots are supply pads and upgrade them and the bases until I have 3 free building slots for barracks then a reactor and a field armory. (Still testing a few different methods for normal with all debuff skulls) It can be tough to try to build up your bases and keep your units and transports alive at the same time, but I try to get my resources first. I try to hide away weak units until I have the economy to heal them and the transport ships. 3. I go around the map getting resources and killing more enemies. The base by the Covenant I put anti-air turrets and upgrade them so they hopefully kill a few drop ships and Covenant troops. I try to get ODST's ASAP so I can scrap the barracks for something else and put ODST's in all the towers. Maybe I will upgrade the hornets. I've been testing on making Cobras from the base by the Covenant one to take out some of their units/turrets. 4. Hope all goes well and turn on all the debuff skulls for the last 20 seconds. Co-Op makes things easier to micromanage, plus a couple free warthogs to start with.