How do I get out of Soul Form?

I'm playing Demon's Souls, and dying a lot. I've seen a message that says "while in soul form, your HP is halved." Other than starting a new game and not dying, how can I get out of soul form?

In order to turn back into Body Form from Soul Form, you need to either:

• Kill a boss
• Invade someone else's game as a Black Phantom and kill the host
• Use a Stone of Ephemeral Eyes
• Become summoned as a Blue Phantom and kill the boss
• Become summoned as a Blue Phantom and kill the host of the game

I wouldn't worry too much about being in Soul Form. It's definitely not necessary to start a new game, as you will likely end up dying again anyway. In fact, if you want to deliberately shift World Tendency, you will probably end up purposefully killing yourself more than once. Many people spend most of their game in Soul Form in order to minimize the effect on their World Tendency.

Hint: Wearing the Cling Ring in Soul Form, your health is only reduced by 25% rather than 50%.