For Facebook
Create a page for your niche / keyword .
Post some pics , articles , tag your friends in that pic or article .
Create a POLL and again tag your friends . Try to use social media exchange to get some likes on your page and activity.
Join various groups related to your niche / keyword , leave your fanpage link with description .
Join some L4L , S4S groups and pages and leave your fanpage link there that you can get likes ans shares for your page and post .
repeat the process.
For Twitter
Create a complete profile ( No Egg Profile ) , follow similar users having followers list of atleast 500 .
retweet there popular tweets .
Post image related to your niche / keyword.
One more important thing there is daily limit of following , unfollowing, like , share , etc on every social media site , try to follow the rules and get organic traffic on your blog , website , page , profile etc.
Use # tag to get more attention .