Some stuff to watch for:

• Write the votes into an external file (flat text file would usually do the trick)
  It should look something like:

          $vote = 'somefile.txt';
          open (VOTE, "+>>$vote") or die "Cannot open output file: $!\n"
  +;
          seek VOTE, 0, 0;
          while (<VOTE>) {
              # you read the votes here and put them into appropriate va
  +riables
          }
          
          # increment the voting.
  
          seek VOTE, 0, 0;
          truncate $vote, 0;
          # print your votes back to the file.
  [download]

• Do not cache your pages by including a header, and usually an HTML meta tag helps like:
  <META Http-Equiv="Pragma" Conent="no-cache">
• beware of people voting too many times.. you should not allow someone who just voted to vote again and again..

You could also post some code.