Web capitalization?

In web design, you have to deal how to treat headers, field names and links within a form. I seem to struggle with it everyday. The question always comes down to how I should apply  capitalization?  From example, in a simple form where a user has to fill out basic personal information (first, last, email,...) can be treated in a number of different ways. Example 1 - Capitalize first letter of first word only

Your information

First name:

Last name:

Email address:

Work phone:

Cell phone:

I like this approach the best because it's more conversational. Almost as if you are reading a book.

Example 2 - Capitalize first letter of all words

Your Information

First Name:

Last Name:

Email Address:

Work Phone:

Cell Phone:

I like this approach less because the capitalization on every first letter interferes which readability. Each word is given the same weight.

Example 3 - Capitalize all letters

YOUR INFORMATION

FIRST NAME:

LAST NAME:

EMAIL ADDRESS:

WORK PHONE:

CELL PHONE:

I really don't like all-caps. The readability is terrible. There is no flow. Every letter has the same weight. The capitalization style also poses problems for action hyperlinks.

Example 1: Add new category

Example 2: Add New Category

Example 3: ADD NEW CATEGORY

There are rules around this from a print aspect (The Chicago Manual of Style), but they don't take interaction into consideration. Is there a good guide out there? Currently it seems to be all over the board.