The Devil’s Playground
The trick of this mission is the lava flow. Keep building on high ground, and only move your command centers around the map. When lava is about to rise, evacuate low ground. You will need a mixed force to protect your workers from Zerg waves, which are quite strong on high difficulties and will always ignore your main base and go for the mining operations.
Your SCV can be loaded into Command Centers in case of emergency, and the COmmand Centers can take off with the SCV inside. Use this to avoid losing workers early on, when your forces will be thin. Mercenaries are quite effective on this map.
If you destroy all Zerg buildings on this map, you will be rewarded a Feat of Strength.
Welcome to the Jungle
You will need two forces for this mission. One to escort your SCV while they gather terrazine, and one to prevent the Protoss from closing the altars.
The enemy will attack you with large numbers of Colossi, Void Rays and Scouts. Although the Goliath is a "recommended" unit for this mission, you should pay attention to Stalkers and Scouts. They can take out Goliaths really fast.
It’s so Easy: You will need Reapers for this one early in the game. Use them to quickly move around the map and snipe the Probes. Keep doing this until you have enough forces to directly attack the mining operations.
Appetite for Destruction: While this is pretty straightforward to complete, remember that any SCV loss will disqualify you for this achievement.
Breakout/Ghost of a Chance
This are RPG-like missions. All you will have to do is control your heroes and protect them from detectors. Using abilities correctly is the key to victory.
The Advantages of Ghosts
Ghosts are powerful snipers with bonus damage against light units. Their attacks are long ranged are their nukes deal more damage. With research, they can stay invisible forever, without draining their energy. Garissoned inside bunkers, they will gain enough range to shoot at Brood Lords and Colossi, making them very useful in missions with lots of zergs. If you plan on doing the air version of All-in, then choose Ghost.
The advantages of Specters
Specters are the assault versions of Ghosts. They have a little shorter range (1 range less), but they are also have more hit points, and posses a powerful area of effect spell and a stun spell. Like their ghostly counterparts, they can stay invisible forever provided you buy the research. Very potent against protoss, as they deal bonus damage against armored units.