Best practices for using mysql field names.

CASES:

1>Type1
Code:
---------
users
---------
id
first_name
last_name
email
password
----------
VS

2> Type2

Code:
---------
users
---------
user_id
user_first_name
user_last_name
user_email
user_password
----------
ie prefixed with singular table name : user


I would like to know the opinions of forumians that which naming conventions (among two as shown above)
do you deploy and why?

Thanks