Chapters of Fire Emblem: Path of Radiance/Chapter 1: The Battle Begins
This a strategy for the "Easy" difficulty in the game.
As soon as you start the battle, the other three members of your party (Titania, Oscar and Boyd) will tell Ike about the Weapon Triangle. This helps you figure out which enemy to attack, however, due to the difficulty, this isn't needed until later chapters.
Titania has the greatest range for this chapter, but try not to use her if possible. You might want to let her visit the homes, instead of battling. She's already a Level 1 Paladin, so she is your only pre-promoted unit at this time. Don't use her, and give the Exp. to Oscar, Boyd and Ike. They're going to need it for the rest of the game, while she can stay off on her own.
Now, for the actual battle section. Send Boyd to the southwest (below the first house on your left), so he can slowly take out the first enemy. Send Ike forward for now, and send Oscar to the Northwest. There is no way to stop the Bandit from burning down the house, so don't even attempt. Oscar and Boyd may be able to attack this Player Phase, but Ike will not be able to during your first turn unless you choose to move him to the Southwest instead of Boyd. Send Titania into the first house to get a sword, which can be traded to Ike when they get next to each other on the battlefield. Next, the Bandits will move. The one nearest to Boyd will attack Boyd, and the one nearest to Oscar will attack Oscar. Others may move towards any of your three characters (Ike, Oscar and Boyd) in their range. The boss will not move, so don't worry about him right now. When it's your turn, have Boyd attack his enemy (he may kill him), and have Oscar move to the north. This will get him close to the boss, but don't target the boss yet. Do your best to clear out the rest of the field. On your next Player Phase, get everyone where Oscar and Ike are. Disregard the boss until every other Bandit on the field is cleared out.
When you finally reach the boss, you shouldn't have much trouble with him. If you use Ike or Boyd, you may need a Vulnerary. You shouldn't need one if you use Oscar or Titania. Ike will get much-needed Exp. (explanation in the "Notes" section), and everyone else will get dummy Exp. (explanation in the "Notes" section). He's not too hard to beat, so just kill him and seize the spot with Ike. If you get on the section with anyone else, they will be healed slowly.
Notes: Much-Needed Exp. - They need the Exp. because they are promoted through the storyline, and it's best to get them to Level 20 as soon as possible.
Dummy Exp. - They need the Exp., but not as much. They can be promoted anytime after Level 10 with the use of a Master Seal. When they reach Level 20, level them up one more time, and they shall change Classes. Their Level will start over at 1, and they get a nice stat boost.