This information is more geared towards players with a less robust troop collection. If you have access to the troops, Madd Frost's guide is beyond sufficient using the egg thief team.
The main point is being able to find what you have available. On your troop screen, press (Y) and search through some of these terms: any color(brown), create, select, convert, troll. "Select" is particularly good for this as it gives you control to keep extra turns going, and troll troops are nice as many double a specific color of gems on the board. Double converts, like Qilin, or anything that adds skulls are not advised as you may win too quickly.
This is the team I went with:
Crysturtle
Cockatrice
Titan Hero (Mountain Crusher)
Apothecary
I feel brown is the easiest to go with as cockatrice keeps the enemy from doing anything to you and mountain crusher pops the board and can sustain a dust storm if you have it leveled up. Blue may be next easiest, but you should build the team around which color "select" troop you have.
Explore is the way to go and you shouldn't need to do level 12 as you wont damage near as much as the egg thief team.