Depending on the prize that you are trying to win, here is a little trick for entering more points per day.

Sign up each member of your household with their own email address.  You can enter up to 10 codes per day per account.  Codes are not transferable between accounts so this will not work if you are aiming at a large prize, but so far this has worked for my husband and I.

It takes 80 points for 500 Delta sky miles - with caps you can earn 1000 miles in 3 days, and still have some points left over.  With the 10 pointers you could receive 1000 miles per day and have points left over.

The code that you receive from Coke for the Delta miles can be used by anybody - you can even sell it here on Ebay.