Question about keyword in Title tag

How much time i can put my main keyword on title and description for better increase ranking?
example:

Title: My keyword: Your Source to My Keyword
Description: My Keyword. All You Need To Know About My Keyword.

Or Just One Time:

Title: Your Source to My Keyword
Description: All You Need To Know About My Keyword.

Which is better to rank?

Only once,don't go twice.Also use website auditor for onpage seo

Put once in Title tag for sure, but it doesn't really matter if you put it in Meta description tag or not. SE have stopped considering meta tags in rankings