After you thwart Team Aqua/Magma on Mt. Chimney and walk south through Jagged Pass, you reach Lavaridge Town.
Talk to the old woman in front of the hot springs to receive a Wynaut egg. Wynaut is a Psychic-type pokémon.
Talk to the man outside of the Herb Shop to get a free Charcoal, which will strengthen a pokémon's Fire-type moves if held.
The herbs in the shop have healing properties, but they are bitter, so they reduce the friendliness of the pokémon that eat them.
In Emerald, in the house next to the Herb Shop, a boy will teach the move Mimic to a pokémon. He only will do this once, ever, so choose wisely. Mimic will copy the move last used by the opponent pokémon. The mimicked move is known only temporarily: it is forgotten after the battle or if the mimicking pokémon faints or is switched out.
Challenge the Gym
Lavaridge Town is home to the Lavaridge Gym, where Gym Leader Flannery specializes in Fire-type pokémon. Fire pokémon are weak to Water, Ground, and Rock moves. Challenge the gym when you're ready.