How to promote business using Social network marketing.?

First, you share useful information and/or free stuffs for people/followers, build relationship with others users, while you promoting your brand/product/service.
The most effective social media sites right now I think is Facebook, Twitter and Pinterest.

Facebook & Pinterest are the most relaible social networking sites, popular nowadays.

Make an account in twitter, and start following people so they follow you back (to increase followers). and start advertising your site on twitter. the followers you get are only for making good impressions for the upcoming real followers.

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There are many ways to utilise this, and it is best to go with a few, Facebook has excellent targeting for ads, far more sophisticated than Google and the sheer user volume should make this a must. Twitter can be very lucrative, Pinterest is growing fast, but also utilise things like Digg, Delicious and Stumbleupon, these can also bring a lot of traffic your way. With each of them, read up and find out exactly what you can do to use them effectively, they can have huge potential...

Your login shoul be your business name
link your social site with your own business
Upload Images of Your Products
Offer Prizes for Contests
Try to engage With maximum users

First of all, you need to make good list of friends, be active on social networking sites such as Facebook, Twitter etc. it would help.

First of all, you need to create profiles on social media site, increase number of friends, post useful stuff, these would help.