Contest is the easiest medium to attract readers to your blog. With a little investment, you get a lot in return like increase in readership, traffic and comments. But not all contest get the desired results.
Success of a contest is very important to get the maximum goods of it. Bloggers always wonder that what should they do to make their contest a success. Here are some points i have learned while organizing and sponsoring a number of contests.

How to make your blog contest a success

1. Its all about the prizes

Prizes are the core of a contest. If your prizes suck, your contest will too! Prizes are like magnets for readers. Good ones attract a horde, Bad ones scare away even the few that come their way. So a lot depends on the type and the number of prizes you give.
It is always better to give out hard cash than any other service or product (even if it has the same worth) because your readers may or may not like the product your giving but they will always like the money(Actually it’s all about the money :) ).
Number of prizes also matters, if you have prizes to give to 10 different people then it increases their chances of winning and hence increases the participation.

2. Make it Super Easy

Contests having a lot of requirements is a sure way to repel people. Contests having few requirements and easy tasks have the best turnout. For example, it is a one minute job to subscribe to your blog, but is at least an hour job to write a whole review about your blog. So obviously more people are likely to subscribe than write a review.

3. Make it a regular feature

Organizing contests on a regular basis increases participation. After certain time period the contests become known to a bigger audience and hence one gets a huge turnout after 1 or 2 contests. And the best about this is that it also converts a number of casual readers into serious blog readers.

4. Random is the way to Go

This is a bit debatable, but in my opinion contests which select winners on a random basis get a better response than the ones that require people to be best at something (eg. Have the best review or the Top commentator). For the sole reason that via Random, anybody can win(i.e have equal chance of winning) but via the other methods, only the ones that are leading have higher chance to win.

5. Broadcast

The most important step is to let others know that you are organizing a contest. A simple way is to tweet about it, if you have a good following say about 5000 then atleast 80-200 people will get to know about and the figure may shoot up if there are further retweets.
Secondly you can post your contests in popular contest blogs i.e blogs that post about latest contests online. These blogs have a huge number of followers who are eager to participate in new and interesting contests.
Another time consuming but effective solution is to contact some authority bloggers. It is a bit tedious but if you contact a number of bloggers, you mind end up getting some reviews of the contest.

Have you organized a contest on your blog? What has been your experience?