There are different ways like :--
1) you can check the field width for minimum and maximum.
2) If that field only take the Numeric Value then check 
it'll only take Numeric no other type.
3) If it takes the date or time then check for other.
4) Same way like Numeric you can check it for the 
Character,Alpha Numeric aand all.
5) And the most Important if you click and hit the enter 
key then some time pag e may give the error of javascript, 
that is the big fault on the page .
6) Check the field for the Null value ..
ETC.....................

The date field we can check in different ways
Possitive testing: first we enter the date in given format
                   
Negative Testing: We enter the date in invalid format
   suppose if we enter date like 30/02/2006 it should 
display some error message
and also we use to check the numeric or text

The date field we can check in different ways

Possitive testing: 
first we enter the date in given format
                   
Negative Testing: 
We enter the date in invalid format
LIKE:
suppose if we enter date like 30/02/2006 dd-mm-yy it should 
      "Display some error message"
 
If we enter date LIKE mm-dd-yy, (  -dd-yy), (mm-  -yy), (mm-
dd-  ), if mandatory of the field (  -  -  ). format 
  and also we use to check with text data

          "It should display warning mesg"

Here are some
1) 00/00/0000 ---> invalid
2) 11/11/2006 ---> valid
3) 32/12/2003 ---> invalid
4) 12/13/2006 ---> invalid

Also check for the leap year

check for the valid and invalid number of days in each 
month if there is no date picker or calender provided.

For eg: enter 30/02/2007

a) Leap Year
b) Non Leap Year
c) Editable Date: Day part should not be greater than 31 
days & month not greater than 12
d) Date Foramt
e) Previous & Future dates
f) System date & Blank date

addition to try to enter 29 for feb month if the year is 
not a leap year...i.e dd/m/year as 29/02/2007.this time we 
would get error message.

display of date should based on the selection format.

When we are identifying the date field in a website we need
to concentrate on the positive and negative test cases

Validation on Year,Month,Date
Validations on date range
Validations on format of the date system accepting
Validations On Min and Max date range